Top seed James Blake beat Japanese wildcard Kei Nishikori 6-4 6-4 at the US Clay Court Championships to set-up a clash with teenager Ryan Harrison.
World number nine Blake had been beaten by teenager Nishikori in this year's Delray Beach final, but gained revenge with a comfortable win.
"It definitely feels good any time you can avenge a loss," said Blake.
"He's an excellent player and at 18 years old he's got a huge learning curve and will continue to get better."
Harrison, 15, shocked Uruguay's Pablo Cuevas on Monday to join Spaniard Rafael Nadal and Frenchman Richard Gasquet as the only players since 1990 to win ATP matches under the age of 16.
Blake now faces a second teenager as he prepares to take on Harrison in their second round match on Thursday, with the youngster feeling confident of another shock win.
"I feel like I have a good chance," Harrison said. "If I play at the level that I played two days ago, then I have a chance for a win."
Fourth-seeded American Sam Querrey made an early exit from the tournament as he was beaten 5-7 6-4 6-4 in a marathon battle against Nicolas Massu.
Querrey had led 2-0 in the deciding set but Chilean Massu edged the match, which lasted two hours and 48 minutes.
"I played well and it could have gone either way," Querrey said. "It was a tough match. I didn't serve my best but, other than that, it was pretty good.
"I'm not too disappointed."
Massu now goes up against Brazil's Marcos Daniel, who was a 6-3 6-4 winner over Serbian Viktor Troicki.
Third-seeded American Mardy Fish moved into the third round of the competition after crushing compatriot Hugo Armando 6-3 6-2.
In other first-round matches, Australia's Peter Luczak beat qualifier Harel Levy of Israel 6-4 6-4 and Chilean Paul Capdeville brushed aside Argentina's Diego Hartfield 6-0 6-4.
Eighth-seeded Spaniard Oscar Hernandez scraped past American Donald Young 6-4 6-4 in a second-round clash.

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