DELRAY BEACH, Fla. -- Mardy Fish upset No. 3 seed Marcelo Rios of Chile 6-3, 6-4 in the semifinals of the International Tennis Championships on Saturday to set up an all-American final.

Fish, ranked 66th, will play No. 4 seed Jan-Michael Gambill in the final Sunday. Earlier in the day, Gambill struggled to a 6-3, 2-6, 7-6 (5) victory over fellow American Robert Kendrick.

''It can only help me feel I belong out here,'' said the 21-year-old Fish, who won his first career semifinal match. ''Rios is a former No. 1 and has established himself as a tour veteran. He knows what to do and it was only my first semifinal.''

Fish, who posted 11 aces in the semifinal, won four of the final five games from 2-2 in the first set. In the second set, Fish also won four of the final five games from 3-2 for Rios.

''I have no experience in this situation,'' Fish said. ''I tried not to think about it and just play tennis.''

The 25-year-old Gambill, who won the second of his two career titles at this tournament in 2001, started to cramp after playing for nearly two hours.

The 162nd-ranked Kendrick won his first three career ATP Tour matches this week.

''I think he has a good game,'' Gambill said of Kendrick. ''That match could've gone either way. It's exciting to see another young American playing well.''