Second-placed Schalke 04's title chances appeared to have been severely dented when they lost 4-2 at relegation-threatened Hanover 96 earlier on Saturday but they were given fresh hope of overhauling the leaders after Bayern dropped two points.
Dutch winger Arjen Robben put Bayern ahead in the 51st minute with a penalty after Franck Ribery was brought down but Leverkusen levelled eight minutes later through Arturo Vidal.
The hosts could have snatched victory in the final minute when Swiss striker Eren Derdiyok pounced on a backpass by defender Martin Demichelis but was denied by goalkeeper Hans-Joerg Butt.
With four matches left, Bayern, who are also in the German Cup final and in the last four of the Champions League, have 60 points. Schalke are on 58 and third-placed Leverkusen have 54.
"We have had so many matches in the past weeks and we are still two points ahead. I can only be satisfied," said Bayern coach Louis van Gaal.
Bayern looked sluggish from the start, their energy reserves seemingly drained by their Champions League away goals win over Manchester United on Wednesday.
UNLUCKY LEVERKUSEN
Livelier Leverkusen came close through a Derdiyok header before fellow Swiss international Tranquillo Barnetta rattled the post with a thundering right-footer.
The visitors took the lead early in the second half when Robben netted his 11th league goal of the season from the penalty spot.
Leverkusen levelled in the 59th after hitting the woodwork twice in a span of a minute, through Stefan Kiessling and Toni Kroos. Arturo Vidal was quick to stab it in for the equaliser on the rebound after Kroos' free kick rattled the bar.
Leverkusen coach Jupp Heynckes admitted their Bundesliga title hopes were all but gone.
"I think now we have to start looking behind us. Although overall I think we deserved to win today."
Fourth-placed Borussia Dortmund, on 52 points, failed to close in after losing 1-0 to Mainz while Werder Bremen crushed Freiburg 4-0 to come within a point of Dortmund.
At the other end of the table Hertha Berlin slumped to a 1-0 defeat by VfB Stuttgart and now have only slim chances of staying up.
