Sharks fullback Riaan Viljoen scored in injury time to deny the Blues a first win in nine years against the Sharks.
The hosts won 22-20 after leading 17-5 at halftime.
The Sharks were dominant in the first 20 minutes and led 14-0. The Blues struck back in the second half to lead 20-17 but Viljoen turned a miserable afternoon into a memorable one when he stepped inside Rene Ranger to snatch victory.
It was the Blues fourth successive defeat and the win is a boost for the Cheetahs’ prospects of a top six finish.
Sharks – Tries: Marcell Coetzee, Charl McLeod, Riaan Viljoen. Conversions: Pat Lambie (2). Penalty: Lambie.
Blues – Tries: Frank Halai (2), Rene Ranger. Conversion: Chris Noakes. Penalty: Noakes.