Defending champion Milos Raonic made it back set win over American Ryan Harrison on Saturday.
Raonic, 21, beat Harrison 7-6 (7-4), 6-2 in just 78 minutes on the hardcourts at HP Pavillion, firing 20 aces in the match and winning 84 percent of his service points.
He saved the only break point he faced and improved to 1-1 against the 19- year-old Harrison, who beat Raonic last year at Indian Wells.
Later, Istomin bounced back from a loss in a second set tiebreaker to down Benneteau 6-3, 6-7 (4-7), 6-3 in a match that went 2 hours and 20 minutes.
Istomin, 25, fought off 10 aces and topped the Frenchman for the first time in three all-time meetings. Benneteau, 30, was 2-0 against Istomin after beating him at last year's U.S. Open.
The winner of Sunday's final will earn $95,860.