Zulte-Waregem leapfrogged Anderlecht into top spot of the Belgian First Division following their 2-1 win over the defending champions.
Anderlecht started Sunday in first place, having accounted for Lokeren 3-0 inmidweek but goals from Mbaye Leye and Bernard Malanda-Adje ensured the hosts moved ahead of their rivals.
Zulte-Waregem made a solid start to proceedings and they were rewarded with a 14th-minute penalty, which Leye converted.
Adje put the result beyond doubt 10 minutes from time, although Dieumerci Mbokani set up a nervy finish after pulling a goal back in stoppage time.
There are five games remaining in the end of season play-offs and next up for the new league leaders is an away trip to Standard Liege.
Elsewhere on Sunday, Genk suffered their second defeat in a week after losing 2-0 at home to Club Brugge.
Genk were beaten 3-0 on Tuesday by a superior Standard Liege outfit and they walked away empty-handed again following goals from Brugge duo Carlos Bacca and Eidur Gudjohnsen.