Chang had rallied from 4-1 down in the third set to beat Jim Courier in a gruelling semi-final, but the wear-and-tear of that took its toll on Sunday night against a well-rested Agassi.
In winning the first set, Agassi breezed through a stretch in which he won 19 out of 21 points, breaking Chang twice and establishing clear dominance.
It carried over into the second when three straight aces put Agassi 40- 0 up while serving at 0-1. But Chang then suddenly won five straight points, breaking Agassi for the first time to go 2-0 up.
Agassi, clearly frustrated, started missing with his first serve. Chang responded with another break and won four of the next five games to take the set and level the match.
At break-point with Chang serving at 1-2 in the third set, Agassi produced a strong, unreturnable forehand. Chang came close to breaking back when he led 40-30 at 2-4 but Agassi won three straight points to hold serve. Chang then saved three match points at 2-5 and another at 3-5 before Agassi closed it out when Chang netted a return after a long rally.
"It's very difficult to put Chang away in two sets," Agassi said. "You cannot play Chang one-dimensionally. You have got to mix it up." Agassi last lost to Chang in 1993 at Cincinnati.
Agassi, 24, has won both tournaments he has entered this year, having won the Australian Open in January. Since the start of last September's US Open, which he won as an unseeded player, Agassi has now won 34 and lost just two singles matches.
The San Jose title puts him within 643 points of Pete Sampras at the top of the world rankings; the pair are next scheduled for the same tournament in Philadelphia from 20-26 February.
THE WORLD'S TOP FIVE: 1 P Sampras (US); 2 A Agassi (US); 3 B Becker (Ger); 4 G Ivanisevic (Croat); 5 M Chang (US).Reuse content