Exeter fought back from 13 points behind for a second week running to see off a determined effort from Harlequins and hang on to second place in the Gallagher Premiership table, winning 21-20.
A Danny Care-inspired Quins performance, based on some superb defensive work, looked like inflicting a third loss in four home games on the reigning European and Premiership champions.
However, two tries in the final quarter saw Exeter turn the game on its head, with the second from Dave Ewers marking his 150th Premiership and European appearance for the Devon side.
Exeter made a very bright start to the game and Quins were indebted to try-saving tackles from Marcus Smith and Care to deny Joe Simmonds and Tom O'Flaherty after impressive bursts by the Exeter duo.
It was somewhat against the run of play, therefore, that Quins took the lead, with back-rowers James Chisholm and Alex Dombrandt combining very well in midfield to send scrum-half Care racing away for a try, converted by Smith.
Exeter suffered a blow just past the midway point of the half when experienced centre Ian Whitten limped off with a right leg injury, to be replaced by Ollie Devoto.
However, within a minute of the Irishman's departure, Exeter were back on level terms with their visitors. A neat move at the front of a line-out saw scrum-half Stuart Townsend force his way over in the corner, and Simmonds converted confidently from close to the touchline.
Quins enjoyed a strong finish to the opening period as the Chiefs' mistakes mounted up, and they were rewarded with a Smith penalty to put their noses in front at 10-7 at the break.
Quins, who had won five of their previous six games, extended their advantage seven minutes into the second half with a try by hooker Scott Baldwin from a catch-and-drive line-out, with Smith improving the score.
And it looked like they had wrapped the game up when a clever Care grubber kick put Ben Tapuai in for a score under the posts after Quins had destroyed Exeter's scrum, but television match official Luke Pearce spotted a knock-on at the base, and with referee Craig Maxwell-Keys already playing a penalty advantage, Smith kicked the three points for a 20-7 lead.
Exeter's error-strewn performance started to improve, and when England prop Harry Williams forced his way over after a quick tap penalty by Townsend, and Simmonds converted, the Chiefs were right back in it at six points adrift.
Then, with five minutes remaining, man of the match Ewers forced his way over to score, and Simmonds' boot put Exeter in front for the first time in the match, and they held on for victory.
