Gareth Steenson struck a penalty in the 79th minute to clinch a remarkable 40-39 victory for Exeter against Gloucester in front of a full house at Sandy Park.
The win ensures the Chiefs will play in the Heineken Cup again next season, along with their West Country rivals, who finish a place above them in fifth spot in the Aviva Premiership table.
In a pulsating encounter, Freddie Burns appeared to have won it for Gloucester when he squeezed in at the corner for his side's fifth try before adding the conversion to put them 39-37 ahead. But Steenson had other ideas, landing the decisive penalty in the dying moments to take his own tally to 25 points.
Bath's 23-14 defeat at Saracens meant Exeter were secure in the top six in any case, but the result means the home side maintained their position as league leaders at the end of the regular season. Chris Ashton, Mako Vunipola and Owen Farrell scored tries for Saracens, with the rest of their points coming from the boot of Farrell. Rob Webber and Horacio Agulla crossed for Bath, with Tom Heathcote converting both. Saracens take on Northampton at home in the play-off semi-finals next weekend.
London Welsh brought the curtain down on their spell in the top flight with their first league win since the start of December. The Exiles, already relegated, defeated Worcester 33-22 at home, courtesy of tries from Dan Caprice, Alfie To'oala, Tom Arscott and Nick Scott, with Gordon Ross kicking 13 points.
Christian Wade scored twice to take his total to 13 league tries this season but could not prevent Wasps from losing 21-20 at Sale. Nick Macleod kicked a penalty five minutes from time to snatch the win from Dai Young's side, who had been leading 20-18.
Despite the defeat, Wasps may still qualify for the Heineken Cup due to French clubs' dominance of Europe this season. With Clermont Auvergne and Toulon in the final of the main competition, victory for Stade Français in the Amlin Challenge Cup final against Leinster on 17 May would hand Wasps a Heineken spot by virtue of their European ranking.