Sam Querrey beat Alejandro Falla for the second time in less than a week, defeating the Colombian 6-3, 6-3 in a first round match at the US National Indoor Championships on Tuesday.
Querrey, who won the Memphis title three years ago, hammered six aces and won 74 percent of his first-serve points as he needed just 58 minutes to eliminate Falla.
Fourth seed Querrey also beat Falla in the quarter-finals of the San Jose tournament on Friday.
Querrey, who is the No. 2 ranked American on the ATP Tour, advances to the second round where he will face the winner of a match between Japan's Go Soeda and Marinko Matosevic of Australia.
Defending champion Jurgen Melzer crashed out of the joint ATP and WTA tournament, losing his opening-round match in straight sets at The Racquet Club of Memphis.
The left-handed Austrian lost to Dutchman Igor Sijsling 6-4, 7-6 (7/3).
Sijsling advanced to a second-round match against Croatian top seed Marin Cilic.
Melzer, who was playing with a broken toe, defeated Milos Raonic in last year's final, snapping the Canadian's win streak at nine straight matches.
In the late match, Japanese fifth seed Kei Nishikori cruised past Ilya Marchenko 6-4, 7-5.
American veteran James Blake defeated German Florian Mayer 4-6, 6-3, 6-2.
On the women's side, Slovakian seventh seed Magdalena Rybarikova reached the third round by ousting American Lauren Davis 7-6 (7/2), 6-2.
France's Claire Feuerstein upset Czech fifth seed Lucie Hradecka 6-3, 6-4 while German third seed Sabine Lisicki reached the second round with a 7-5, 6-3 victory over American Madison Keys.