Updated

Andy Roddick served 20 aces Tuesday to defeat 21-year-old American qualifier Rhyne Williams 6-3, 6-4, 6-4 in the first round of the U.S. Open.

Roddick, seeded 20th, won the last 16 points on his serve and finished the match with a 127-mph ace.

It was a tough way to make a Grand Slam debut for Williams, the NCAA runner-up in 2011, who won three matches in qualifying, then learned he had a first-round matchup with the 2003 champion in Arthur Ashe Stadium.

Williams, ranked 289th coming into the week, put in a respectable performance, but dropped a break in each set. He'll still earn $23,000 as a first-round loser in the year's final Grand Slam.