Since the 2003-04 Champions League season, 13 teams have won the first leg by three or more goals, as Bayern Munich did last week. Those teams are 8-1-4 in the second leg (62 percent).
The chances of Barcelona overturning the deficit is even more remote. In the 139 knockout ties since 2003-04, the only club to advance after losing the first leg by three or more goals is Deportivo La Coruna in 2004. It lost the first leg 4-1 to AC Milan, and won 4-0 at home in the second leg to win the tie 5-4.
Here's the odds and notes for the second leg of the Champions League semifinal courtesy of Bet365.com:
Barcelona v Bayern Munich -120 +333 +300
* Barcelona has to beat Bayern Munich by five goals to qualify for the final. A 4-0 Barcelona win after 90 minutes will take the tie to extra time, and if no goal is scored in extra time, the tie will be decided by penalties. If Bayern scores once, Barcelona has to score six goals.
* Barcelona midfielder Sergio Busquetes is in a fitness race to play on Wednesday. He missed Saturday's La Liga game against Athletic Bilbao with a groin problem and did not train on Sunday.
* Bayern Munich has won 10 games in a row and 21 of its last 22 matches in all competitions.
* Barcelona fullback Jordi Alba is suspended for the second leg and defender Javier Mascherano is also expected to miss out. Marc Bartra, who struggled in the first leg, is expected to partner Gerard Pique in the center of defense.
* Barcelona has won 10 games this year in all competitions by four goals.
* Bayern Munich hasn't lost a game in any competition by four goals or more since April 8, 2009. (Barcelona 4 Bayern Munich 0)