The 23-year-old was forced to take a year out after suffering a serious knee injury in 2008 but has impressed ever since returning in December and was at it again against the Blues.

Rennie and full-back Jim Thompson touched down for Edinburgh while 11 points from the boot of ever-present Scotland international Chris Paterson wrapped up the win.

Ceri Sweeney hit back with three penalties as did Wales international Leigh Halfpenny with one but it wasn’t enough for an out-of-sorts Cardiff outfit.

The visitors started the brightest at Murrayfield with Sweeney trading two penalties in the first 20 minutes with Paterson.

But from then on in Edinburgh took control with Rennie and Thompson scoring either side of half-time.

A penalty apiece from Sweeney again and Halfpenny gave Cardiff hope after 64 minutes – but it wasn’t to be with Paterson’s boot having the final say four minutes later.