Serbia's Viktor Troicki came through a tough battle with America's Michael Russell to book his place in the second round of the Power Horse Cup in Dusseldorf.
Russell claimed a topsy-turvy first set that saw both players broken on multiple occasions, but seventh seed Troicki hit back to force a decider.
It would prove a tense and close affair, but a single break proved enough for the Serbian as he eventually closed out a 3-6 6-3 6-4 victory in an hour and 54 minutes.
Eighth seed Nikolay Davydenko was on the wrong end of a three-set scoreline as Slovenia's Aljaz Bedene shrugged off the loss of the opening set to record a surprise 3-6 6-4 6-3 win.
Another Slovenian, Grega Zemlja produced a fine display to defeat promising Belgian youngster David Goffin 5-7 6-0 6-2.
Meanwhile, Holland's big-serving Igor Sijsling emerged a comfortable 6-2 6-4 winner against Evgeny Korolev of Kazakhstan.