Vienna - John Isner became the first player to advance to the quarter-finals of the Erste Bank Open on Wednesday by beating former champion Feliciano Lopez 7-6 (1), 3-6, 7-6 (2).
The 27th-ranked American failed to break the Spaniard's serve.
Isner missed a match point at 5-4 and again at 6-5 in the final set before dominating the tie-breaker and closing out the win on his 31st ace.
"The match was so close. My served helped me a lot," said Isner, who reached his fifth quarter-final of the season.
In first-round play, Philipp Kohlschreiber of Germany rallied to beat Stephane Robert of France 4-6, 6-3, 7-6 (3), and Albert Ramos-Vinolas of Spain advanced with a 6-2, 6-2 win over Italy's Fabio Fognini, who had not lost to Ramos-Vinolas in eight previous matches.
Results from the ATP Vienna Open on Wednesday (x denotes seeding):
John Isner (USA) bt Feliciano Lopez (ESP) 7-6 (7/1), 3-6, 7-6 (7/2)
Ivo Karlovic (CRO x8) bt Damir Dzumhur (BIH) 7-6 (8/6), 4-6, 7-6 (7/5)
Karen Khachanov (RUS) bt Nikoloz Basilashvili (GEO) 6-2, 7-5
Andy Murray (GBR x1) bt Martin Klizan (SVK) 6-3, 6-7 (5/7), 6-0
Philipp Kohlschreiber (GER) bt Stephane Robert (FRA) 4-6, 6-3, 7-6 (7/3)
Albert Ramos (ESP) bt Fabio Fognini (ITA) 6-2, 6-2