Lyon ties Marseille, holds onto second
After just eight minutes, the latter's Mathieu Valbuena released Modou Sougou inside the penalty area but his effort was deflected behind by defender Milan Bisevac.
Two minutes later, Valbuena combined with Andre-Pierre Gignac with the latter's effort skimming the post.
After 21 minutes, Andre Ayew crossed towards Sougou whose header found Gignac. The striker went for the spectacular with his overhead kick falling just wide.
The visitors were well on top and Sougou released Rod Fanni on the right channel before he freed Gignac, whose shot was caught by goalkeeper Remy Vercoutre.
Lyon finally awoke after the restart and six minutes in created their first chance. Steed Malbranque released Gueida Fofana on the edge of the box with his effort hitting the outside of the post before going behind.
Midway through the second half, Alexandre Lacazette released Bafetimbi Gomis but his effort from 12 yards out was pushed around the post by Steve Mandanda.
The stopper also kept out Samuel Umtiti's effort from the resulting corner as the game drew to a frustratingly uneventful conclusion.
The young striker scored from close range in the 12th minute and again in the 24th as his side bounced back in style from last week's 4-0 defeat to St Etienne.
Montpellier pressed in the second half and hit the woodwork through Younes Belhanda, but the reigning champions could not find a way back into the game.
It was one-way traffic at the Stade Chaban-Delmas and, after Ludovic Obraniak had struck the crossbar, Diabate grabbed the opener having come off the bench for the start of the second half.
The win lifts Bordeaux one place to ninth, while Bastia remain just three points above the drop zone.