(CNN) -- Bayer Leverkusen stumbled to a fifth draw in seven games but still extended their lead in the German Bundesliga to four points with a 0-0 stalemate at Hannover on Saturday.
Second-placed Werder Bremen can cut the gap on Jupp Heynckes' unbeaten side to one point with victory at Cologne on Sunday, having been joined on 27 points by Bayern Munich -- who defeated Borussia Moenchengladbach 2-1 on Friday night.
Hannover won their first point since the death of goalkeeper and captain Robert Enke to move up to 12th place, five points clear of the relegation zone.
The closest Leverkusen came to scoring was when Stefan Kiessling's second-half effort was cleared off the line by Konstantin Rausch.
Hamburg moved up to fourth place on goal difference ahead of Schalke, two points behind Bayern and Bremen, after being held 0-0 at home by Hoffenheim.
The visitors are a point behind on 24 along with Borussia Dortmund, who crushed second-bottom Nuremburg 4-0 at home after scoring three times in the first 36 minutes.
Defending champions Wolfsburg are eight on 23 points after being held 2-2 at home by Freiburg, needing an 81st-minute equalizer from Fabian Johnson to avoid defeat as they twice came from behind and twice hit the crossbar.
Under-pressure Stuttgart boss Markus Babbel saw his side remain in the bottom three after conceding an 89th-minute leveler in the 1-1 draw at home to fellow strugglers Bochum.
Germany defender Serdar Tasci's 63rd-minute header gave Stuttgart hope of a first league win since September, but Austria defender Christian Fuchs earned a point when he beat goalkeeper Jens Lehmann with a stunning free-kick.
It's a big week ahead for Babbel, whose side must beat Romania's Unirea Urziceni at home on Wednesday to progress from Group G in the Champions League.
Eintracht Frankfurt were to host Mainz in a mid-table clash in the late match.