Underneath Quins, it was 'all change' at the top with Saracens slipping into second spot, Gloucester to third.
A controversial last-minute Tom Casson try ensured Harlequins regained top spot in the Premiership with a hard-fought 31-28 victory over London Irish on Sunday afternoon.
Guy Armitage's debut Premiership try, after Ben Botica's kick was charged down, gave Irish a brief lead before Danny Care's interception score.
Botica and Ian Humphreys continued their shootout after the break as Tom Williams got Quins back out in front. Casson's try, which he looked to have knocked on, was given by the video ref.
London Wasps claimed a try bonus point as they beat London Welsh 29-19 in the two clubs' first ever league meeting.
Two tries apiece from Christian Wade and Tom Varndell lay the foundations for the victory in a match in which Wasps never fell behind.
However second-half tries from Phil Mackenzie and Franck Montanella kept the Exiles in contention.
Welsh looked to have secured a losing bonus but were denied by a late penalty from former Sale Shark Lee Thomas.
Saracens knocked Northampton off the top of the Premiership with a businesslike 16-6 win at Franklin's Gardens.
Owen Farrell and Stephen Myler exchanged three points early on before Alex Goode crossed for the only try of the game, which Farrell converted.
Ryan Lamb booted Saints to within four points after the break but the hosts tried to force their game in vain.
Two more Farrell penalties gave Sarries a 10-point lead which condemned Saints to a second successive domestic defeat.
Gloucester held off a late Leicester onslaught for a fifth Premiership win in a tumultuous clash at Kingsholm.
Charlie Sharples' first-minute try set the tone, Scott Hamilton replied for Tigers, before Freddie Burns produced a memorable individual score.
Akapusi Qera's try, after James Simpson-Daniel's sublime run, put Gloucester in control after the break.
Tigers won a penalty try, with the hosts down to 13, but despite sustained pressure could not break through. Final score 27-21.
Bath continued their 34-year unbeaten record against Exeter Chiefs with a gutsy and pulsating 23-15 Premiership win.
Early Bath tries by Ben Williams and Kyle Eastmond were answered by Brett Sturgess in a flowing first half.
Stephen Donald and Gareth Steenson traded penalties either side of the break but Francois Louw's try gave Bath a 12-point cushion on the hour.
The hosts went down to 14 men when Dan Hipkiss was sent off for a second yellow card and Ignacio Mieres's try set up a tense finale.
The result sees Bath leapfrog Exeter into sixth place in the Premiership and extends the Chiefs' run of defeats away from home to six in all competitions.
London Irish's losing bonus point takes them to ten points, alongside the Welsh, both eight points clear of Sale Sharks.
The Irish are the next visitors to Salford City Stadium on Friday 2nd November, kick off 8.00pm. Buy your tickets online.
