Federer has beaten del Potro all six times they have met this season, though he was pushed to his limits on Centre Court at Wimbledon in August. Federer won 19-17 in the decisive third set.
"I'm excited to see how he is going to come out and play," Federer said of Sunday's final. "We have had a couple of tough ones, at the French Open and particularly at the Olympics. I had a really hard time breaking his serve. The margins are extremely small."
Del Potro let a two-set lead slip in their quarterfinal at Roland Garros, and took the first set at the Olympics before losing the second on a tiebreaker.
"I was close in the Olympics and French Open but I never beat him this year," said the eight-ranked del Potro, who rebounded from the tough Olympics loss to win his bronze-medal match. "He has all the shots. He's a very, very complete player."
Federer, chasing his sixth title in seven years at his hometown event, fired 10 aces and never allowed 101st-ranked Mathieu a break-point chance.
Excellent anticipation at the net put Federer into position to hit a volleyed winner to create two set points in the first. He clinched with a forehand winner.
Federer moved his opponent around the court in the final game before putting away an overhead to earn match point, and sealed his victory when Mathieu netted a two-handed backhand.
Federer has a 13-2 career record against del Potro, though one of the Argentinian's victories came in the 2009 U.S Open final. A wrist injury then wrecked his 2010 season.
"Now he is finally back to his real self again," Federer said. "He looked really impressive today."
Del Potro, who won the Vienna title last week, said his play against Gasquet was "almost perfection. Now I have to play better tomorrow if I want to win this tournament."
His eighth ace sealed his 61st victory of the season, a career best. Del Potro improved to 16-1 on indoor hard courts in 2012, with his only loss coming against Federer in the Rotterdam final in February.