Bristol Bears had to settle for a 27-27 draw against 14-man London Irish following a frenetic finish at Ashton Gate.
The Bears had ended the previous round of fixtures top of the Premiership pile, but results went against them on Saturday as Northampton Saints reached the summit with a bonus-point success.
And Bristol's hopes of climbing back above Northampton were hindered by a dogged Irish display the following day, the promoted outfit playing for 40 minutes a man down.
The home side struggled to get going early on and trailed 7-3 at the break after Ben Meehan's try, although they were boosted by a red card for Ollie Hoskins as his shoulder made contact with Chris Vui's head.
Nathan Hughes and Charles Piutau crossed following the restart and the Bears appeared to be in control.
However, Waisake Naholo intercepted to race through and score for Irish, kickstarting a frantic spell.
Ed Holmes scored in style for Bristol, then John Afoa was sent to the sin bin and Tom Parton had Irish back in front again, only for Harry Thacker to cross three minutes from time.
Stephen Myler dispatched a last-gasp Irish penalty and there was no time for the Bears to rally once more, able only to climb to second.
Sunday's other fixture was a similarly tight affair, but Harlequins got the better of Gloucester 23-19.
Ross Chisholm and Alex Dombrandt went over for Harlequins, with an Ollie Thorley double and Ben Morgan's try coming in response.
Marcus Smith's third penalty with the final play of the game made the points safe.