This season's UEFA Champions League has once again been a joy to watch. We have witnessed some fantastic football and some outstanding individual performances. This week sees two eagerly awaited semi-final first leg encounters. Bayern Munich host Barcelona at the Allianz Arena on Tuesday, whilst Borussia Dortmund entertain Real Madrid the following evening.

We can look forward to the prospect of two of the most mouth-watering and intriguing semi-final clashes for years. Bayern, Barcelona, Borussia Dortmund and Real Madrid all play exciting, attacking football. The dominance of Spain and German clubs in this year's Champions League reflects the position in international football where these two countries currently sit at the top of the Fifa Coca-Cola World Ranking. The task of predicting which of these four great clubs will emerge victorious and progress to the showpiece final at Wembley on May 25th to claim the greatest prize in club football is extremely difficult.

Let's have a look at what we can expect in the Bayern Munich and Barcelona tie.

This contest between two giants of European football has the added intrigue of Pep Guardiola, the illustrious former Barcelona and soon to be Bayern manager, lurking somewhere in the shadows. There has been speculation, perhaps inevitably so, that Pep will be Bayern's secret weapon. Jupp Heynckes has vehemently denied this, and sounded affronted by the suggestion that he would need Guardiola's guidance.

What to expect

We have in prospect a fascinating tie between two great exponents of the short passing game, with plenty of open, attacking football and no shortage of technique and skill. Each side seeks to dominate ball possession. According to statistics compiled by WhoScored?com, Barcelona and Bayern are the top two sides in Europe, averaging 69.3% and 63.9% respectively in La Liga and the Bundesliga. The picture is slightly different in the Champions League where, whilst Barça maintain a 68% average possession, Bayern's average slips to 57%. According to the UEFA website, in this season's competition Barcelona have attempted almost 8,000 passes (almost 25% more than Bayern and over 30% more than either Dortmund or Madrid) and can boast an impressive 83% pass success rate compared to Bayern's, almost equally impressive, 76%.

However, ball possession and pass completion rates won't automatically guarantee a team success. There are a number of other factors to consider.

Firstly, despite averaging 38 minutes per game possession time, Barcelona have scored 18 Champions League goals compared to Bayern's 22 from their average 34 minutes of possession in each game. And, importantly, despite having less possession, Bayern have had more goal attempts - an average of 16.7 per game (7.7 on target), slightly better than Barça's 15.7 (6.6 on target).

Set pieces are another factor to consider because they can have a major bearing on the outcome of games. Bayern have won an average of 8.9 corners per Champions League game (by far the highest of all the semi-final teams), compared to Barcelona's 6.6 per game. The Bayern and Barcelona teams have suffered the most fouls, 15.1 each per game, the highest of the semi-finalists. Barcelona, however, concede significantly fewer fouls at only 8.7 per game as opposed to Bayern's 13.7 per game, higher also than Borussia Dortmund and Real Madrid.

Bayern Munich

Bayern were last season's losing finalists. In the eyes of the purists, football was the loser because Chelsea's ultra-defensive, negative, counter-attacking style of play spoiled the spectacle. Chelsea had, of course, employed the same approach to stifle and overcome Barça in the semi-finals.

Bayern's manager Jupp Heynckes previously managed Real Madrid to Champions League success in 1998, an achievement of great significance given that it was Madrid's first title in European competition for more than 30 years.

Bayern have been in ominous form this season. Their summer ventures into the transfer market have been a huge success, particularly defensive midfielder Javi Martinez (€40m from Athletic Bilbao), striker Mario Mandzukić (€13m from VfL Wolfsburg) and central defender Dante (€4.5m from Borussia Mönchengladbach).

Bayern clicked together immediately this season. After being runners-up in the Bundesliga to Borussia Dortmund for two previous seasons, this time they performed well from the outset on both domestic and European fronts. Bayern sealed their 23rd Bundesliga title weeks ago. And after winning their Champions League group on goal difference from Valencia and defeating Arsenal in the round of 16, Bayern were the standout team of the quarter-final matches. They completely dominated a much-heralded Juventus side, winning both legs of the tie and scoring twice in each game past a normally watertight Juve defence.

5 Bayern Munich Players to Watch

1. Bastian Schweinsteiger
The 28-year old who already has 98 caps for Germany is a dominant, influential player at the heart of the Bayern midfield. He has been described by his team-mate Mario Gomez as Bayern's 'midfield motor'. He is an intelligent player with great technique. His Champions League pass success rate this season stands at 88.1%, Formerly a winger, he also possesses great dribbling skills. He reads the game well and has a decent scoring record, with 2 Champions League goals and 3 assists this season, and 7 goals and 3 assists in the Bundesliga.

2. Toni Kroos
The 23-year old Kroos is another highly intelligent player in the Bayern midfield. Already a well-established German international, he possesses excellent technique, including great ball control, passing and movement. In this year's Champions League his pass success rate is 85.1% and he has scored 3 times in 8 games.

3. Javi Martinez
Javi Martinez, Bayern's record signing from Athletic Bilbao has been a revelation this season. He is physically powerful, reads the play well and is widely regarded as one of the best defensive midfielders in Europe. He is also creative and versatile. He has performed well in his role in front of back four but can also play in central defence or as creative midfielder. His pass success rate in this year's Champions League is an impressive 88%, not far behind his Spanish international team-mates Xavi Hernandez and Iniesta of Barcelona.

4. Thomas Müller
German international attacking midfielder Muller, with 41 caps at the age of 23, burst onto the international scene at World Cup in 2010. He is extremely pacy with great technique and a keen eye for goal. He is blessed with a great knack of being in the right place at the right time and has scored 5 goals in the Champions League this season.

5. Franck Ribery
In French international Ribery, Bayern have a tricky and extremely gifted left-sided player who is capable of conjuring brilliant moments in a game. The mercurial Ribery has been described by French football legend Zinadine Zidane as the "jewel of French football". He has great vision, pace, dribbling and crossing abilities and a sharp eye for goal, having scored a hugely impressive goal every 3 games in his 150 games for Bayern.

Suspension

Mario Mandzukić, Bayern's industrious and skilful Croatian striker misses the first leg of the semi-final due to suspension. He will be missed, having scored 15 times in 19 Bundesliga appearances and twice in the Champions League.

Barcelona

The success enjoyed by Barcelona since their Champions League win over Arsenal in 2006 has been little short of remarkable. They have now progressed to the European Cup/Champions League semi-finals a record eight times and have won the title a record 3 times in the past decade. Barça's success reached new heights in domestic and European football after the appointment of Pep Guardiola in 2008. He won 14 titles in 4 years before resigning his post last year. So how poignant, then, that now his sabbatical from football is almost over and his return to management at Bayern next season has been agreed, the spectre of Guardiola looms large over this tie.

Current Barcelona manager Tito Vilanova has successfully picked up the mantle from Guardiola. Unfortunately, he has been forced to miss part of the season after cancer surgery and lengthy rehabilitation. Barcelona have performed brilliantly domestically and are on the verge of winning the title back from Real Madrid. However, despite winning their Champions League group, they have struggled at times in this year's competition. They were given a fright in both games against Celtic. And they almost got a bigger fright in the round of 16 tie against AC Milan but rescued the day with another Messi-inspired performance in the home leg, winning 4-2 on aggregate. They reached the semi-finals after being given a thorough examination by Paris Saint-Germain and were rescued by a partially-fit Messi, summoned from the bench to save the day.

5 Barcelona Players to Watch

1. Lionel Messi
What is there to say about this player? Maybe calling him a genius would not suffice. He is the world's greatest player and his four Ballon d'Or, World Footballer of the Year, titles confirms this. His goalscoring record is simply incredible - in 2012 he scored 91 goals in a single calendar year. He has scored 8 goals in this season's Champions League. The only worry for Vilanova and his team is whether Messi will be fully fit after his recent injury.

2. Xavi Hernandez
Again, what more can be said about this little midfield genius that has not already been said many thousands of times? He is possibly the greatest and most complete midfield player in history. He is Barcelona's heartbeat, their conductor and driving force. He possesses sublime technique and brilliant vision. In this season's Champions League he has already created 30 goalscoring opportunities and has a pass success rate of an astonishing 95.3%. Against Paris Saint-Germain in the quarter-final second leg he did not misplace a single pass. This is little short of astonishing.

3. Andres Iniesta
Iniesta is Xavi's perfect foil. At 28, he is five years younger than his illustrious midfield partner. Possessing sublime technique in his passing, movement, dribbling and shooting Iniesta is a player who can be relied upon to deliver in big games. He memorably scored the goal that won the World Cup final for Spain in 2010. His pass success rate in the Champions League this season is an amazing 91.6%.

4. Sergio Busquets
Sergio Busquets is a defensive midfielder with a brilliant ability to pass, read and make interceptions. His positional play shows great intelligence and he works tirelessly with and without the ball. He is the pivot in the Barcelona midfield, often responsible for initiating and linking their tiki-taka style of play. His pass success rate in the Champions League this year is 92.3% - bettered only by Xavi's near perfect rate of 95.3%. He has the ability to play in a number of positions, including centre back, and always looks comfortable.

5. Pedro
Pedro is a forward who has become an intregal part of the Barcelona team. He can play on either flank, has great pace and skill and creates goals. Although he has only one Champions League goal to his credit this season, he has the potential to win matches. He has an impressively high pass success rate of 90.1% and is a key element of Barça's tiki-taka style.

And Finally...

In prospect we have a Champions League semi-final which promises plenty of open, attacking football. It will be fascinating to observe how Barcelona's tiki-taka style fares against Bayern's high energy, pressing game. How will Barça cope with the threat from Bayern's super-fast counter-attacks and set pieces? The task of predicting which side will emerge victorius from the two legs is a real challenge. But there is one thing we can be sure of - football fans everywhere can look forward to two thrilling games between two of the world's great sides involving some of the most exciting and exhilarating players in the history of football.



The majority of statistics cited in this article were used with kind permission from WhoScored?com (www.whoscored.com)