BRISTOL, England (Reuters) -Harlequins kept their nerve to overturn a 28-0 deficit and stage the biggest comeback in Premiership history, stunning Bristol Bears with a 43-36 semi-final win in extra time on Saturday.
Quins will face Exeter Chiefs in the Twickenham final on June 26, after the defending champions saw off Sale Sharks 40-30 in the day's second semi-final.
The Bears, who finished top of the league to secure home advantage for the final-four clash, made a bright start with flyhalf Callum Sheedy scoring back-to-back penalties.
Two tries from Max Malins, and one each Ben Earl and Luke Morahan, put Bristol 28-0 up in as many minutes before Alex Dombrandt responded for the visitors on the stroke of halftime to go in at the break at 28-5.
Harlequins dominated the second half as Tyrone Green, James Chisholm and Louis Lynagh went over to cut the deficit to 28-24, before Joe Marchant's late try sent the game into an additional 20 minutes at 31-31.
Green and Marchant scored either side of Malins's third to seal a remarkable win as Harlequins progressed to their first Premiership final since they won the title in 2012.
"We worked so hard for this but it's a small achievement compared to what we want to achieve next week," said Green, who was named man of the match.
Harlequins general manager Billy Millard said he could not bring himself to watch the final few minutes of the match and sat in the dressing room.
"We were hanging on for dear life but we just about did enough," he told BT Sport. "We just knew that if we could get some momentum on the scoreboard, Bristol might buckle. It's just unbelievable the spirit from this side and group."
Exeter reached their sixth consecutive final after dominating the game from the early exchanges, with Luke Cowan-Dickie, Tom O'Flaherty and Jack Nowell scoring tries to give them a 22-13 lead at halftime.
Sale, hoping to reach a first Twickenham showpiece since 2006, had their moments at Sandy Park, with Rohan Janse van Rensburg's second try after the break keeping them in the contest.
But Alex Cuthbert scored late on as Exeter maintained the upper hand to remain on course for back-to-back Premiership titles for the first time in their history.
(Reporting by Hardik Vyas in Bengaluru;Editing by Andrew Cawthorne and Clare Fallon)