Exeter Chiefs have overcome Saracens with a thrilling 42-28 victory at Sandy Park.
Gareth Steenson, starting in place of Ignacio Mieres, kicked an early penalty to give Exeter the lead.
Harlequins had a chance to strike back through Nick Evans, whose poor kicking cost Quins against Saracens last week, but Evans kicked his effort wide.
Evans was given a second penalty opportunity five minutes later, and this time took full advantage to level the scores.
A line break from Luke Arscott set up a resulting breakdown and the ball was sent wide to Brett Sturgess, who gave the Chiefs a 10-3 lead.
Steenson and Evans again exchanged penalities before the Quins fly-half pounced on a Steenson kick to touch down and pull the score back to 13-11.
Exeter extended the lead with another penalty but, shortly before the beak, consistent Quins pressure allowed Ugo Monye to break through and give Quins an 18-16 half-time lead.
The Chiefs regained the lead early in the second half, with a pitch-length move sending Ben White over for a try.
The lead exchanged hands once again, with Rory Clegg intercepting to send Harelquins' Karl Dickson under the posts.
Once again Exeter hit back, this time through Jason Shoemark, who scored two brilliant tries to give the Chiefs a 10-point lead at 35-25.
Rory Clegg put Harlequins within seven points with a late penalty but big Sireli Naqelevuki powered over late in the game to secure a memorable 42-28 victory for the Chiefs.
