Harlequins overcame a significant half-time deficit to claim a stunning 28-24 triumph at Twickenham and dent Gloucester’s play-off hopes.
The Cherry and Whites were outstanding in the first half, going 24-7 ahead thanks to tries from Ben Morgan, Freddie Clarke and Chris Harris, but they wilted after the break.
George Skivington’s men made far too many errors and the comeback kings duly benefited. Quins, to their credit, were much improved in the second period and Joe Marchant’s brace, allied by further scores via Alex Dombrandt and Cadan Murley, meant Quins confirmed their Premiership top-four place.
The West Country club remain fifth – level on points with Northampton – and in play-off contention ahead of their final regular-season game against Saracens on June 4, but they will see their trip to Twickenham as a huge missed opportunity.
Quins made their intentions clear after they gained a kickable penalty in the opening minute, but Smith opted for touch and an attacking lineout in pursuit of a try, before Gloucester cleared.
The visitors also showed plenty of early endeavour, with Harris prominent and wing Ollie Thorley twice given chances to run at the Harlequins defence.
And Gloucester struck first on the scoreboard, executing one of their trademark driven lineouts to set up an imposing attacking platform before Morgan touched down, with Hastings converting.
But it took Quins just five minutes to respond as centre Marchant’s surging run was only halted by a Louis Rees-Zammit tackle, yet quickly recycled possession created space for Dombrandt to cross from close range, and Smith converted.
A fast and furious opening quarter still had one more scoring act, though, and this time it was Gloucester’s creativity that left Quins reeling.
Full-back Santiago Carreras weaved his way clear and then delivered a superb inside pass to Clarke, who sprinted 30 metres, brushing off Louis Lynagh’s attempted tackle and then celebrating with a Chris Ashton-style dive.
Hastings’ conversion made it 14-7, yet despite Quins’ deficit, they refused to be shackled and full-back Huw Jones’ invention deserved more than a Lynagh knock-on.
Gloucester then showed their opponents how it should be done, handling brilliantly before skipper Lewis Ludlow got behind the home defence and delivered a scoring pass to Harris.
Hastings converted and then landed a drop-goal six minutes before the break, opening up a 17-point advantage, and Quins’ misery was underlined by Dombrandt spilling possession deep inside Gloucester’s 22.
Harlequins needed a rapid response in the second period and they threated after Morgan limped off, but an error allowed a Gloucester counter-attack that was only thwarted by Marchant’s tackle on Thorley.
Marchant brought Quins back into the contest, gathering scrum-half Danny Care’s clever kick and claiming a try converted by Smith that set up an enthralling final 30 minutes.
Marchant then struck again entering the final quarter, with Smith’s conversion closing the gap to just three points and asking serious questions of Gloucester, especially after Rees-Zammit was yellow-carded following a deliberate knock-on.
Quins were now well and truly in the mood, and they went ahead for the first time when the away side ran out of defensive numbers and Murley crossed unopposed, with Smith again converting.
In their final game of the season, the Exiles knew a bonus-point win would cement their position in Europe’s top-tier for 2022/23, but they were hit by a late sucker punch.
Declan Kidney’s men are still three points ahead of Wasps – the only team that can overtake them – but the Coventry-based outfit have one final match to play.
However, that comes in the form of an away game against a dominant Leicester Tigers outfit. It means that Irish are still the favourites, but they will have to wait another week for their fate to be confirmed.
The Exiles seemed to be suffering no ill-effects from their agonising midweek Premiership Rugby Cup final defeat to Worcester when they scored a fourth, bonus-point try soon after the break.
But a Will Muir try and two penalties by Orlando Bailey, who also kicked three conversions, saw Bath fight back for a only their fifth win of the season.
The West Countrymen now face a shoot-out on June 4 with Worcester, three points adrift, to decide who ends up bottom of the table.
Tries from Nemani Nadolo and Guy Porter, bolstered by the boot of George Ford, secured the points for the table-topping Tigers, with Freddie Steward scoring late on.
Hooker George McGuigan did cross for Falcons but the hosts slipped to a 16th defeat of the season and remain 11th in the Premiership table.
Eddie Jones on youngster Henry Arundell
England head coach Eddie Jones talks about form London Irish full-back Henry Arundell.