John Isner has booked his place in the second round of the Madrid Open thanks to a straight-sets triumph over Russian qualifier Teymuraz Gabashvili.
Isner dominated the opening set, but the American failed to convert five break points before squandering a set point at 6-5.
However, the world number 10 managed to compose himself in what was a nervy tie-break to clinch it 10-8.
An early break saw Isner take control of the second set, and he was able to hold serve to secure the victory 6-4 with nearly two hours on the clock.
Isner will now meet either Australian Marinko Matosevic or Germany's Philipp Kohlschreiber in the next round.
