Convincing win for Isner
Top seed John Isner booked his place in the third round of the Winston-Salem Open with a straight-sets victory over Bradley Klahn.
The world No 15, who earlier on Tuesday was seeded 13th for the US Open, beat his fellow American 7-5 (7/5) 6-2.
Joining him in the third round is second seed Kevin Anderson, who booked his place with a hard-fought victory over Adrian Mannarino.
The South African world number 20 took the first set but Mannarino stepped up his game in the second and forced a decider before Anderson kept his composure to win 6-3 2-6 6-4.
Third seed Tommy Rebredo crashed out of the tournament after a straight-sets defeat to Nicolas Mahut.
The Frenchman made a blistering start to the match, dropping only one game as he took the first set before clinching the second and the match on a tie break to win 6-1 7-6 (7-0).
Fourth seed Leonardo Mayer joined Rebredo in making an early exit as he was also sent packing in straight sets. David Goffin was his conqueror, with the Belgian winning 6-3 6-1.
Fifth seed Guillermo Garcia-Lopez fought back from a set down to defeat Germany's Dustin Brown 6-7 (5-7) 6-2 6-2, while sixth seed Joao Sousa exited the tournament after Jerzy Janowicz won their match 6-1 3-6 7-6 (7-5).
Lukas Rosol, the No 7 seed, is also out of the tournament after being forced to retire while trailing Ryan Harrison by a set, while eighth seed Marcel Granollers was a 6-3 6-3 winner against Paul-Henri Mathieu.
Ninth seed Yen-Hsun Lu beat Blaz Rola 6-4 7-5 and 10th seed Pablo Andujar won 6-4 6-3 against Igor Sijsling.
No 11 seed Donald Young had one of the easier paths to the third round, beating Canada's Frank Dancevic 6-1 6-3 to progress.
Edouard Roger-Vasselin, seeded 12th, was also taken to three sets but advanced at the expense of Aleksandr Nedovyesov thanks to a 7-6 (11-9) 6-7 (5-7) 6-4 victory.
Mikhail Kukushkin, the No 13 seed, lost the opening set against Robin Haase but fought back to earn a 5-7 7-6 (7-2) 6-4 triumph, while 14th-ranked Andreas Seppi was taken the distance before he safely advanced. The 30-year-old Italian drew on all his experience to beat Federico Delbonis 7-5 6-7 (4-7) 6-2.
Fifteenth seed Jarkko Nieminen was another ranked to progress after he beat Benjamin Becker 7-5 6-4, while Sam Querrey secured a shock 6-4 6-3 victory against 16th seed Steve Johnson.