Nick Evans marked his final outing at Twickenham Stoop by steering Harlequins to a 32-13 victory over Wasps, but the win was marred by Danny Care's stomach muscle injury.
Care lasted only 25 minutes before being forced off for treatment, giving Eddie Jones a scare ahead of England's June tour to Argentina.
The Quins captain was one of two scrum-halves picked in the squad to face the Pumas over two Tests, but his misfortune could open the door for Wasps' Dan Robson who was unfortunate to miss out on the squad.
Uncapped Exeter 20-year-old Jack Maunder was picked in his place, but Robson ran in a brilliant first-half try started by Jimmy Gopperth with Jones watching from the stands.
Evans retires at the end of the season and he bade farewell to Quins fans by booting 22 points in a match of the match display in front of his family that keeps alive the club's Champions Cup qualification hopes.
Wasps were overwhelmed on territory and possession, and finished the evening well beaten to end their five-match winning run and forcing them to wait until the final round to ensure a home play-off.
Quins raced out of the blocks and made ground with strong carries from Joe Marchant and Mike Brown, but they were assisted by an accommodating visiting defence.
Evans opened his account with a penalty and when he sent a high kick down the throat of Willie le Roux, jeers greeted the South Africa full-back's failure to catch a simple ball that evoked memories of his butter-fingers against Leinster in Dublin last month.
An overlap went begging when Chris Robshaw failed to keep off Evans' long, floated pass, but in the 25th minute Wasps showed their rivals how to finish when they ruthlessly exploited a defensive lapse from Quins.
Brown's kick was caught by Gopperth and the Kiwi dashed through a hole in the chasing line before off-loading to Robson who sprinted over the whitewash.
To rub salt into the home team's wounds, Care limped off immediately after and into the breach stepped veteran Karl Dickson, who also retires after next Saturday's Premiership finale at Northampton.
Four minutes into the second half Quins propelled themselves back into the match when Kurtley Beale went for an intercept only to be beaten by the flight of the ball. Robshaw scooped it up, drew the last man and expertly found Tim Visser who galloped home.
Evans converted and added a penalty to nudge the 2012 Premiership champions 16-10 clear and when le Roux was sin-binned for taking Marchant out in the air, they had moved nine points ahead. Joe Launchbury followed le Roux into the sin-bin for killing the ball after Marchant had fallen just short of the line but Marchant crossed with two minutes left to earn his reward.