Quins and Leicester claim wins
Harlequins beat Bath 19-16 to snatch a Premiership play-off spot on Saturday, while Leicester beat Saracens to secure third place.
Harlequins knew a bonus-point victory would see them jump above Bath as would a victory of any kind so long as the visitors were restricted to one bonus point or less.
Mike Brown gave the hosts a dream start with an early try but his effort was cancelled out by George Ford's excellent solo effort and it was only Nick Evans' penalty that gave Quins a 10-7 lead at the break.
The second period became a battle of the kickers as Matt Banahan's yellow card prompted Quins to take a 16-10 lead and three penalties - two from Ford - left the home side just three points ahead with 10 minutes to play.
Bath pressed and probed in the dying moments, eager to find an opening, but Ford's desperate drop-goal attempt fell short and confirmed Quins' place in the semi-finals where they will play table-toppers Saracens.
Leicester Tigers will travel to great rivals Northampton Saints in the semi-finals next weekend after clinching third place with a bonus point 31-27 win over leaders Saracens at Welford Road.
The reigning champions came out on top in a dramatic 21-minute period either side of half time when six tries were scored, Saracens winger Michael Tagicakibau was sin-binned and flanker Justin Melck was sent off for what appeared to be eye-gouging.
Leicester hit back from 8-3 to take a 10-8 lead just before half time thanks to a penalty try, while further touch downs from Manu Tuilagi, Blaine Scully and Graham Kitchener ensured they took a bonus point.
Saracens' tries came from Ben Spencer (2), a penalty try and Jack Wilson, with Spencer's second four minutes from time earning his side a losing bonus point.
Northampton warmed up for their semi-final with a record 74-13 win over London Wasps.
Jim Mallinder's men were 13-0 down after 15 minutes after tries from Charlie Davies and Tom Varnedell, but came roaring back with 11 tries - a club record - for their biggest ever Premiership win.
Lee Dickson, George North and Phil Dowson scored two each, with Stephen Myler, Luther Burrell, Ken Pisi, Ben Foden and Tom Stephenson also dotting down.
Ryan Lamb landed a late penalty as relegated Worcester edged out Gloucester at Sixways to claim a second Premiership win of the season.
Lamb weighed in with 18 points in total, claiming one of the Warriors' three tries and landing two conversions and three penalties.
Freddie Burns' third and final penalty of the match edged Gloucester, who led 17-15 at the break, ahead but Lamb held his nerve to land the penalty that clinched victory for the home side.
England wing Jonny May scored two tries for the visitors but he and Rob Cook had spells in the sin bin which ultimately proved costly as Gloucester suffered a defeat that saw them drop to ninth place in the Premiership.
London Irish ended their season in style by turning around a 10-point deficit to defeat sixth-placed Sale 22-20.
Irish trailed 20-10 early in the second half but produced a strong performance after the break to stun their visitors who had looked in control of match.
Andy Fenby scored two tries while Marland Yarde also went over for the Exiles with James O'Connor kicking a penalty and and two conversions.
O'Connor also provided two scoring passes and Irish's win would have been greater had he been more accurate off the kicking tee.
Sale scored first-half tries through Mark Easter and Tom Arscott with Joe Ford kicking two penalties and two conversions.
Exeter Chiefs cruised to a comfortable 23-13 win over Newcastle Falcons at Kingston Park to clinch eighth place.
Luke Cowan-Dickie and Ben White grabbed close-range first-half tries to put the Chiefs in charge and ensure the Falcons' run without a Premiership win would be extended to 16 matches.
Henry Slade added a conversion and two penalties for the Chiefs to two from Joel Hodgson before a late flurry saw Fetu Vainikolo add Exeter's third try in the 79th minute and Falcons No 8 Mark Wilson score in stoppage time with Phil Godman adding the conversion.