NEWPORT, R.I. (AP) Denis Kudla beat fellow American Mitchell Krueger 6-4, 5-7, 6-0 in the opening round of the Hall of Fame Tennis Championships on Monday.
Kudla advances to play defending champion Ivo Karlovic, who is seeking his fourth straight finals appearance on Newport's grass courts.
Tobias Kamke won the final three games of the second set to knock out Taylor Fritz 6-3, 6-3. Kamke will play No. 3 seed Adrian Mannarino.
Adrian Menendez-Maceiras beat Stefan Kozlov 6-2, 7-6 (5) to face No. 4 Pierre-Hugues Herbert.
NCAA champion Thai-Son Kwiatkowski lost to Germany's Peter Gojowczyk 6-3, 6-3 in his ATP debut as a wild card.
Top-seeded John Isner, Karlovic, Mannarino and Herbert all received first-round byes. Herbert will be making his Newport debut and Mannarino made a fourth-round run at Wimbledon.
Isner and No. 7 Tennys Sandgren are the only seeded Americans in the field.