Top seed Juan Martin Del Potro marked his return to tennis after a month-long injury absence on Wednesday with a three-hour victory over German qualifier Daniel Brands to reach the Austrian Open third round.
The Argentine defeated Brands 6-7 (5/7), 7-6 (7/4), 7-6 (8/6) in a match featuring 59 aces and no breaks of serve.
The match point -- Del Potro's second -- was decided by the Hawk-Eye electronic system.
"If I'd known I'd have to start with a three-hour win, I would have stayed home," joked the 2011 finalist, who was playing for the first time since suffering a wrist injury in September's Davis Cup semi-finals.
"We both served so well, it was a really tough match," added Del Potro, who kept alive his hopes of booking a place in the eight-man World Tour Finals next month in London which wrap up the ATP season.
The Argentine top seed struggled to find any rhythm in the first set, relying on his serve to stay out of trouble against Brands, the world number 111 who made the semi-finals in 2011.
The German won the opening set only to see Del Potro return the favour in the second, claiming it on a fifth set point.
The final set was also tight before Del Potro pulled it out in another tiebreaker.
"I guess it was a good match to start. I need to count on my serve in the next one. I will have to work on my returns though," said Del Potro.
"I had a few chances today which were hard to take, it all came down to the last point."
Two-time champion Juergen Melzer suffered his earliest Vienna defeat in five years as the fourth seed went out in the second round, losing to Gilles Muller, 6-3, 3-6, 7-6 (7/4).
The result at the Stadthalle was a huge disappointment for the newly-married 31-year-old, his ranking down to 37 after a number of injuries including a hip problem.
Melzer admitted at the start of the week that he was going into the European indoor season with a loss of form, but remained encouraged by his recent Beijing quarter-final run.
But the Austrian was unable to cope with 18 aces from Muller, a Luxembourg journeyman about to turn 30 without a career title.
"I had trouble with my first serves and he was serving very well. He had some real bombs," said Melzer.
"It was not my day out there. I'm sorry to lose so early, especially at home where I've had success."
Melzer, who recently married fellow pro Iveta Benesova, hung tough in the final set to force a tiebreak.
He recovered from 0-3 down in the decider but could do little as Muller unleashed a pair of big serves to wind up the evening, finishing the job with a return winner to the open court.
Dominic Thiem, 19, who ended the career of comeback king Thomas Muster a year ago at the same venue, defeated Slovak Lukas Lacko 7-6 (7/3), 6-3 to keep home hopes alive.