Robert Lewandowski struck on his first return to Borussia Dortmund as Bayern Munich defeated his former side 1-0 in the Bundesliga on Saturday.
Lewandowski claimed the only goal in the 36th minute, heading the rebound into an unguarded net after Roman Weidenfeller saved Thomas Mueller's initial effort. The Poland striker won the ball from Dortmund captain Mats Hummels to get the move underway.
It was a rare chance in a fractious game marred by fouls, yellow cards and broken play.
"Every game is incredibly hard and it gets more difficult with each game. I want to congratulate my players," Pep Guardiola said after becoming the quickest Bundesliga coach to reach 50 wins. The Spaniard needed 61 games, beating Udo Lattek's feat from 78 games.
Marco Reus had Dortmund's best chance on the hour but hit the side netting with only Manuel Neuer to beat, and the Bayern goalkeeper secured the visitors' win with a fine save from Reus' free kick in the final minutes.
Bayern lined up defensively without the injured Arjen Robben, Franck Ribery, David Alaba and Holger Badstuber. Former Dortmund midfielder Mario Goetze only appeared as a substitute, as did Bayern midfielder Thiago Alcantara, who made his comeback from a year out with serious knee injuries.
"Since he came from Barcelona he has only had bad luck and more bad luck and more bad luck," the visibly emotional Guardiola said.
Philipp Lahm and Bastian Schweinsteiger both started the same game for the first time since the World Cup final for Germany. Schweinsteiger, in particular, endured several rough challenges, though the Bayern midfielder gave as good as he got.
Bayern soaked up the home pressure with its packed defense and then posed problems on the break.
Thomas Mueller went close early on when he lifted the ball over Weidenfeller, and Lewandowski had the ball in the net after straying marginally offside. Dortmund failed to heed the warning.
"It's always special to win in Dortmund. They're our greatest rival for the past few seasons," Lahm said.
Defending champion Bayern maintained its 10-point lead with seven games remaining. Dortmund, which was bottom in February, is 34 points behind in 10th.
"We'd just 10 minutes (of good play) in the first half, and then a second half that's OK or good. Well, it's not enough against Bayern," Dortmund coach Juergen Klopp said.
Earlier, Hamburger SV moved closer to Bundesliga relegation by losing 4-0 at Bayer Leverkusen in sports director Peter Knaebel's first game as interim coach.
Knaebel, who took over from the sacked Joe Zinnbauer on March 22, restored Rene Adler in goal, but the former Germany No. 1 was picking the ball out of his net in the seventh minute, when sloppy defending allowed Gonzalo Castro an easy score.
Castro set up Stefan Kiessling in the 44th, then again in the 56th after more poor defending, before completing the scoring on another counterattack in 63rd.
Hamburg occupies the relegation playoff spot could be overtaken by Paderborn on Sunday.
Two goals from Ricardo Rodriguez and Andre Schuerrle's first for Wolfsburg helped their side consolidate second place with a 3-1 home win over bottom club Stuttgart.
Rodriguez's penalty in the 41st minute was cancelled out by Martin Harnik three minutes later, but Rodriguez's free kick from the right evaded everyone in the 65th, and Schuerrle sealed the result with a fine finish to the top corner after some good work from Kevin de Bruyne in the 76th. It was the Belgian's 18th assist of the season.
Third-place Borussia Moenchengladbach came from behind to win 4-1 at Hoffenheim and stay two points clear of Leverkusen.
Didier Ya Konan scored a wonderful late goal to salvage a 2-2 draw for Hannover at Eintracht Frankfurt, easing the pressure on coach Tayfun Korkut.
Werder Bremen drew 0-0 with Mainz, and Mike Frantz's 37th-minute goal was enough for Freiburg to ease its relegation fears with a 1-0 home win over Cologne. Freiburg moved above Hannover on goal difference.