Only one team has managed to overturn a 4-1 deficit after the first leg of a Champions League knockout game - it was Deportivo La Coruna against AC Milan in the quarter-finals of the 2003/04 campaign. They won 4-0 at the Riazor in the second leg.
Borussia Dortmund are unbeaten in their last four encounters with Real Madrid (two wins, two draws). They have met three times in the Champions League this season with Dortmund winning 2-1 and 4-1 at home and drawing at the Bernabeu (2-2).
Real Madrid have won two and drawn one of their three home games against Dortmund in the Champions League.
Borussia Dortmund are the only team unbeaten in the Champions League this season (seven wins, four draws).
Four of Dortmund's five away games in the Champions League this season have ended in a draw.
Real Madrid haven't reached the Champions League final since 2002 while Dortmund's only final appearance was back in 1997 - they were the eventual winners, beating Juventus (3-1).
Real Madrid's games have produced 42 goals (24 for, 18 against), the most in the Champions League this season.
Real Madrid have conceded seven goals in their last two CL games (three v Galatasaray and four v Dortmund).
Real Madrid have won 14 of their 17 Champions League games at the Bernabeu under Jose Mourinho. 10 of these games have been won by at least three-clear goals.
Cristiano Ronaldo is the top scorer in this season's Champions League with 12 goals. It beats his previous best tally in the competition (10 goals in 2011/12).
Ronaldo has scored in each of his last six Champions League games, equalling the record previously set by Marouane Chamakh and Burak Yilmaz.
Ronaldo and Dortmund's Marcel Schmelzer are the only outfield players to have featured in every single minute of this season's Champions League campaign.
Robert Lewandowski has been directly involved in 52% of Dortmund's goals in the Champions League this season, 12 out of 23 (10 goals, two assists). He became the first ever player to score four goals in a European Cup/Champions League game against Real Madrid.
Barcelona - Bayern Munich
No team has ever overturned a 4-0 deficit after the first leg of a Champions League knockout game.
Barcelona's 4-0 defeat in Munich in the first-leg was their heaviest in a Champions League game since their defeat by the same scoreline against Dinamo Kiev back in November 1997.
If Bayern Munich qualify, it will be the third time they have reached the final of the Champions League in the last four seasons. They were beaten finalists in each of their last two appearances (v Inter Milan in 2010 and Chelsea in 2012).
Barcelona have only won one of their seven competitive encounters with Bayern Munich (two draws, four defeats).
Barcelona have won only one of their last six Champions League games (three draws, two defeats).
Worse, they have won only one of their last seven knockout games in the competition (4-0 v AC Milan in this season's last 16), drawing three and losing three.
Barcelona are unbeaten in their last 21 Champions League games at Camp Nou (16 wins, five draws), their last defeat dating back to October 2009 against Rubin Kazan (1-2).
Barcelona's last three home games in the CL knockout stages against German sides have all seen the Catalans win by at least four clear goals: 4-0 v Bayern Munich in April 2009, 4-0 v Vfb Stuttgart in March 2010 and 7-1 v Bayer Leverkusen in March 2012.
Bayern Munich have scored more goals than any other side in the Champions League this season (26).
Bayern Munich have won their last three Champions League games without conceding a single goal, the best current run in the competition.
Arsenal's Laurent Koscielny is the last player to score against Bayern Munich in the Champions League, it was 275 minutes ago.
Thomas Müller has been directly involved in 54.5% of Bayern Munich's goals in the knockout stages of the Champions League this season, six out of 11 (four goals and two assists).
Since 2008/09, Lionel Messi has scored 51 goals in the Champions League, which is 37 more than any other Barcelona player over that period (Pedro, 14 goals).
