Fifth-seeded Kevin Anderson of South Africa came from a set down to beat Bulgaria's Grigor Dimitrov 2-6, 7-6 (5), 7-6 (3) in the first round of the SAP Open on Monday.
In the day's only other singles match, Tobias Kamke of Germany earlier defeated South Africa's Izak Van der Merwe 6-3, 6-3 to advance to the second round.
Former great John McEnroe made a brief return to play an exhibition doubles match on the opening night, teaming with young American Jack Sock to beat Gael Monfils and Steve Johnson 6-4, 6-4 in a lighthearted match.
McEnroe showed the deft skill at the net that made him one of the game's best doubles players ever in a match that included three players young enough to be his children.
"If you know some of the tricks of the trade, I don't care," he said. "I'm covering half the court. This is beautiful for me. I'm not saying I could go out and win things but I'd be comfortable going against anybody right now playing doubles."
McEnroe was originally scheduled to play with defending champion Milos Raonic, who pulled out with a knee injury. Sock ended up teaming with McEnroe, and Johnson, the reigning U.S. college champion, played with Monfils.
Raonic is still expected to compete in the singles draw, starting with his second-round match Wednesday against Kamke.
McEnroe hit crisp volleys all match long, bringing back memories of his touring days when he won seven Grand Slam singles titles and 10 major doubles titles from 1977-92.
Even though he lacks the power of the younger, modern players, McEnroe was able to get his serve up as high as 125 mph - a feat he credited to a friendly radar gun operator rather than some newfound strength.
"I hit one 125 (mph)," he said. "I've never hit it that hard in my life. I owe that guy a dinner."
Perhaps the biggest difference besides the gray hair was the lack of temper tantrums that were such a regular part of his matches when he was on the tour. With the Hawk-Eye replay system in place, McEnroe had little to argue with the umpire or linespeople.
He challenged three calls in the match, winning one of them, and even got down on his belly to closely inspect a mark before challenging a call in the second set that he eventually lost. His only argument came when Monfils won a challenge on a shot that just clipped the back line.
"It's a conspiracy," McEnroe shouted after losing the point.
McEnroe said he would have loved to have had the replay system during his playing career, when he was known perhaps as much for his demonstrative arguments as his sterling play.
"I would have won a lot more majors - in my opinion," McEnroe said. "Forty percent of the energy I wasted in losing it would have allowed me to sort of focus on playing."