Wolfsburg's title dreams were dealt a blow on Sunday as they slipped to a shock defeat.
Felix Magath's side maintain a two-point lead at the summit but missed the opportunity to extend that advantage after going down 2-0 at Energie Cottbus.
Dimitar Rangelov headed the home side in front after 72 minutes and Ervin Skela wrapped up the points three minutes from time.
Cottbus move out of the Bundesliga relegation zone as a result of the impressive success.
Elsewhere, Borussia Monchengladbach were held 1-1 at home by Arminia Bielefeld.
Karim Matmour handed the hosts a 14th minute lead, but Robert Tesche levelled matters on 32 minutes.
Monchengladbach remain second from bottom, without a win in five, while Bielefeld also slip into the bottom three with five games remaining.