Kadir twice embarrassed defender Benjamin Andre as he struck in the 13th and 16th minutes to set up an untroubled 2-0 win for his side.
Lille, one place and one point behind Rennes in sixth, had a similar win as two goals in three minutes by Nolan Roux downed rock-bottom Sochaux as they moved to within three points of the leaders.
Roux opened the scoring in the 34th minute when he slotted home from close range before he headed home Marvin Martin's corner three minutes later as Rene Girard's side moved up to sixth with the 2-0 win.
However, it served to prolong Sochaux's agony as they seek their first win of the season with just two points on the board so far.
Fourth-placed Marseille were held to a second consecutive draw as they struggle to rediscover their early-season form.
Corsica was a happy hunting ground for L'OM last season, but a side whose 100 per cent start to the campaign was ended in a loss to Monaco at the start of the month dropped points for a third straight game on the back of last week's draw with Toulouse.
A point apiece seemed a fair result in a match which saw both teams strike the frame of the goal, with Bastia bossing the first half and Marseille the second.
Evian battled back from two goals down to extend their unbeaten run to three matches after a 2-2 draw with 10-man Montpellier.
The visitors appeared on course to claim just their second win of the season after goals either side of half-time from Victor Montano and Remy Cabella.
But Daniel Wass and substitute Modou Sougou scored in the space of four minutes to earn a share of the spoils, while Montpellier's bad luck was compounded when Siaka Tiene was sent off five minutes from time, despite being earlier substituted, after challenging the referee from the touchline.
Reims remained unbeaten at home and lie seventh thanks to a second-half Nicolas de Preville equaliser against newly-promoted Guingamp.
An Anthony Weber own goal gifted Guingamp an early lead that Reims were only able to cancel out through De Preville once they improved in the second half.