Cardiff Blues continued their improved form to record a narrow 10-3 win over third-placed Edinburgh at the Arms Park.
Dan Fish scored the only try, which Rhys Patchell converted before adding a penalty.
The margin of victory should have been greater but Patchell missed two penalties and the home side did not take a number of try-scoring opportunities which would have rewarded their dominance.
Edinburgh were disappointing and fortunate to come away with a bonus point as they could only manage a penalty from Nathan Fowles.
Cardiff had hoped to include Sam Warburton but neither he nor Gareth Anscombe were released by Wales coach Warren Gatland.
Australia international Salesi Ma'afu made his debut at prop with Matthew Rees, returning from suspension, leading the side.
Edinburgh made 11 changes from last week's defeat in Grenoble, with number eight Cornell Du Preez the only member of the pack to retain his place in the starting line-up.
Back-rower and captain Mike Coman was forced to fill in at lock as the visitors were injury-hit in that position.
The Blues were ahead after only 90 seconds with a splendid try from Fish. The home side gained possession from a scrum in their own half to produce a sweeping movement, which culminated in a well-timed pass from Aled Summerhill sending the full-back over for the try.
Patchell converted with an excellent kick and Cardiff continued to dominate the opening quarter. Powerful number eight Manoa Vosawai was nearly over the try-line on two separate occasions before Patchell put them further ahead with a straightforward penalty.
With their first attack, the Scots got on the scoreboard after 21 minutes when Fowles kicked a simple penalty after the Blues were penalised for offside in front of their own posts.
Back came the Blues into the visitors' 22, where they surprisingly decided not to take three points from a penalty. It proved the wrong option as Vosawai lost the ball in the process of touching down but they maintained the pressure to earn another penalty, only for Patchell's kick to rebound off a post.
Despite dominating the first half, Blues only led 10-3 at the interval and had to face a keen wind in the second half.
Edinburgh suffered a blow when centre Andries Strauss was helped off with a leg injury to be replaced by Will Helu but they overcame this setback to become far more competitive than they were in the first half.
Edinburgh lost a man to the sin-bin when prop Rory Sutherland prevented Tavis Knoyle from taking a quick short penalty.
The third quarter was scoreless and featureless as both sides struggled to bring any continuity to their game.
Patchell missed a good opportunity to become the only scorer of the second half but failed with a routine penalty attempt. The outside half nearly made amends by finishing off a flowing movement to force his way over in the corner but the TMO ruled he had put a foot in touch.