While Tillstrom, a qualifier, gave Rios little trouble in the first set, he broke Rios early in the second set and seemed to be gaining confidence.
Rios was unable to close the match out when he led 6-5 on Tillstrom's serve. The set went to a tiebreaker, which Rios won 7-5.
"What can I say, this is the second year I win this," Rios said. "This is like being home, coming back feeling great, playing some good tennis."
Rios said he wants to improve his ranking and try to stay healthy.
"Right now my goal is to keep fit, not get more injuries. I feel I'm getting back my tennis," he said. "I think these two weeks gave me a nice feeling to end the year with."
Tillstrom said exhaustion from the 10 matches he played this week, including two qualifiers and his doubles matches, hurt his performance.
"In the first set my legs were really tired," he said. "But I came back in the second set and was hitting the ball well."
"I'm very pleased with the way I played, of course after a loss you are disappointed," Tillstrom added. "But I improved my ranking by almost 50 spots this week."
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