The Chiefs and Sarries, who met in last year's final, are both on 15 points after respective victories over Sale Sharks and Northampton Saints.
Exeter, beaten by Saracens in two of the past three finals, ran in five tries in a 35-18 success over the Sharks, while Alex Lewington and David Strettle both scored two tries apiece as the defending champion beat Northampton 38-27.
The Chiefs were able to turn their narrow one-point advantage at the break into a victory as Jack Maunder, Alex Cuthbert and Tom Lawday crossed to add to first-half scores from Santiago Cordero and Jonny Hill.
At Franklin's Gardens, England international Dylan Hartley, starting a competitive game for the first time since March, was one of the try scorers for Northampton, which was leading heading into the final eight minutes.
However, Strettle's late double maintained Saracens' 100 per cent start.
Bath edged a high-scoring affair at the Stoop to claim its first victory as it beat Harlequins 37-32.
Wing Joe Cokanasiga impressed for Bath, dotting down either side of the interval, while Zach Mercer also contributed two tries as the visitors went 37-18 ahead.
Semesa Rokoduguni's trip to the sin bin gave Quins hope and Joe Marler and Charlie Mulchrone went over to reduce the deficit only for Bath to hang on and claim a bonus-point victory.
Newcastle Falcons also claimed its first success of the season, 23-20 against Worcester Warriors, which is now propping up the table as the only remaining winless side.