Bayern Munich were held to a 1-1 home draw by Russian champions Zenit St Petersburg in the first leg of their UEFA Cup semi-final on Thursday.
The Bundesliga leaders led through Franck Ribery's 18th-minute goal but, sorely missing suspended striker Luca Toni, they wasted chances galore.
Brazil defender Lucio deflected a cross from Viktor Fayzulin past Bayern goalkeeper Oliver Kahn for the shock equaliser on the hour that silenced the sell-out crowd of 66,000 at the Allianz Arena on a chilly evening in Munich.
Ribery had first fluffed a penalty when his weak shot was blocked by Zenit goalkeeper Vyacheslav Malafeev but the France playmaker made amends by firing the rebound into the corner.
The return leg will be played in St Petersburg on May 1, with Zenit looking to make the most of their away goal.
The winners will play either Rangers or Fiorentina in the final in Manchester on May 14.
"It's going to be difficult but it's still possible," said Bayern striker Lukas Podolski. "We've got nothing to fear because we're the better team. We played well but were unfortunate to give up a stupid late goal."
Bayern coach Ottmar Hitzfeld told German TV: "We played well at high tempo in the first half. The own-goal was unfortunate but it happens. We've still got a good chance.
"We're always able to score a goal or two away and besides that we've got Luca Toni back in the lineup."
Toni is the UEFA Cup's top scorer this season with 10 goals.
Bayern, fresh from winning the German Cup on Saturday and hoping to clinch their 21st German championship on Sunday, took control from the opening whistle.
Toni, who has scored 35 goals in 41 matches this season, watched from the sidelines after being booked in a two-goal effort in the 3-3 quarter-final draw at Spanish side Getafe.
Germany strikers Lukas Podolski and Miroslav Klose, along with Bastian Schweinsteiger, managed to create plenty of chances, especially in the first half. But their poor finishing and later superb goalkeeping by Malafeev cost them.
Zenit are struggling at the start of the new Russian season, lying 10th in the league with one win and seven points from six matches.
