Leicester Tigers passed up a chance to increase the pressure on the Premiership's leading duo, Saracens and Exeter Chiefs, as they were beaten 10-3 at home by Sale Sharks on Saturday.
Saracens visit Exeter on Sunday, meaning Leicester had the opportunity to close the gap on at least one of the top two this weekend.
However, having been omitted from England's trip to Scotland in the Six Nations, Josh Beaumont captained Sale to victory in a low-scoring affair, registering the only try of the match in the second half.
Difficult conditions had seen the sides go in tied at 3-3 at the interval, with Sale fly-half Danny Cipriani missing five penalty kicks in a row, but the visitors recorded their seventh win in eight matches to go seventh in the table.
It could have been worse for Leicester had Harlequins managed to get the better of Northampton Saints, but it was the visitors who emerged 27-23 victors at The Stoop - Ben Foden going over after the clock had ticked past 80 minutes to clinch the win.
Stephen Myler's early penalty separated the teams at the interval as they shared four tries, before Nick Evans sent Quins in front with a pair of penalties.
JJ Hanrahan and Ben Botica exchanged three-pointers to tee up a rousing finish, but Foden dummied his way to the line to seal victory in dramatic fashion.
The result sees Harlequins stay fourth, while Northampton climb to sixth.
In the day's remaining fixture, Jimmy Gopperth converted a late penalty to earn Wasps a 9-8 victory over Newcastle Falcons.
Andy Goode's wayward kicking against his former club proved costly for the Falcons - the veteran missing two penalties and a conversion at the Ricoh Arena.
Wasps climb back to fifth after being unseated by Gloucester on Friday, leaving Newcastle four points off the bottom.