Top-seeded John Isner outlasted fellow American Jesse Levine 6-4, 7-5 (15) on Tuesday in their first-round match at the Delray Beach International Tennis Championships.
In another first-round match, Jarkko Nieminen of Finland, ranked 43rd, beat second-seeded Marin Cilic of Croatia 6-3, 3-6, 6-2.
Isner barely held off a tenacious Levine, who is ranked No. 133 in the world and needed a wild-card entry into the main draw.
Levine trailed the 11th-ranked Isner throughout the tiebreaker. The match ended when Levine's backhand hit the top of the net and carried long, putting Isner into the second round.
''I served very well and to be honest I was very lucky to win it,'' said Isner, who had 13 aces. ''To be honest, if I lost that second set I didn't really fancy my chances in the third because the humidity was getting to me.''
Nieminen has already won a title this year at Sydney, while Cilic was playing his first match of the season. The 21st-ranked Cilic has been nursing a left knee i...