Tim Swiel added 12 points to guide Harlequins to a surprise 20-9 win over the Northampton Saints, while there were also victories for Bath, Leicester and the Newcastle Falcons in the English Premiership.
Quins came into this match 11th on the log, but the hosts managed to upset the Saints who were in seventh position. Flyhalf Nick Evans squandered numerous chances to put his side in a commanding lead and was replaced by Swiel, with Quins 8-0 to the good. Although Northampton fought back to within two, Swiel nailed four penalty goals in the second stanza to seal a hard-fought win for Quins.
In other matches, Bath hammered the Sale Sharks 30-3 to make it five wins from six so far this season, the Leicester Tigers romped to a 34-13 bonus-point triumph against the Worcester Warriors and the Newcastle Falcons ground out a 19-14 win over struggling Bristol.
The only other match on Saturday saw the Exeter Chiefs snatch a 27-27 draw with Gloucester, courtesy of a last-gasp try. The Chiefs had an opportunity to win the game, but Gareth Steenson missed the conversion.
In a highly anticipated clash on Sunday, Saracens host Wasps in London in the final match of the round.
Round 6 results:
Harlequins 20 Northampton Saints 9
Bath 30 Sale Sharks 3
Leicester Tigers 34 Worcester Warriors 13
Newcastle Falcons 19 Bristol 14
Exeter Chiefs 27 Gloucester 27
Photo: Steve Bardens/Getty Images