FRANKFURT, April 8 (Reuters) - Werder Bremen crushed Bayern Munich 3-0 on Saturday to prise open the Bundesliga title race and cap a bad week for Bayern goalkeeper Oliver Kahn.
Bastian Schweinsteiger headed past Kahn and into his own net in the 33rd minute to hand Werder the lead in Bremen and late goals from Daniel Jensen and Tim Borowski completed Bayern's heaviest league defeat of the season.
Champions Bayern are top on 66 points, followed by Bremen and Hamburg on 59, the latter with a game in hand.
Bayern remain well placed for a 20th league title with five games left but Hamburg can cut their lead to four points if they win at home to Borussia Moenchengladbach on Sunday.
Hertha Berlin are fifth on 43 points after winning 2-0 at third from bottom Kaiserslautern. Cologne, one place lower, beat VfL Wolfsburg 3-0.
The Bayern defeat provided further disappointment for Kahn, who was told by Germany coach Juergen Klinsmann on Friday that his great rival Jens Lehmann would be first choice goalkeeper for the hosts at the World Cup.
Kahn's form deserted him last week in a 2-2 draw with bottom club Cologne that first suggested Bayern might not have the title race sewn up.
They needed a win on Saturday to reassert their authority but even though Kahn looked in good touch and was not at fault on any of the goals, Bayern ended up well beaten.
"I think we played well but things just didn't come off for us," said Bayern coach Felix Magath.
"An away game against Werder Bremen is one you can lose. We're still top of the table."
Kahn pulled off an excellent save in the 15th minute when he was quick to keep out a snap shot from Nelson Valdez.
Bayern gained control in midfield as the game wore on only to gift the home side the lead just past the half-hour mark.
Miroslav Klose did well to anticipate a pass into the area on the left but his cross should have been easily dealt with by Schweinsteiger.
The Germany midfielder, under a bit of pressure from Tim Borowski, attempted to head the ball out for a corner but instead left his keeper with no chance with a powerful header into the top of the net.
Bayern spent most of the rest of the game putting the Werder goal under siege. Martin Demichelis should have made it 1-1 in the 55th minute but he put a free header straight at Tim Wiese.
Two minutes later, Michael Ballack was a fraction wide with a first-time shot from 20 metres.
That was as close as Bayern came. With 10 minutes to go, Jensen tucked in his first Bundesliga goal following a pass from Klose and four minutes later Borowski stroked in from the edge of the box following a third assist of the game from Klose.