Juan Martin del Potro toiled for more than three hours before beating Feliciano Lopez in his first tour match for almost a year Monday at the Medibank International Sydney.
The giant Argentine, who downed Roger Federer to win the 2009 U.S. Open, got just the workout he needed when he ousted the 32nd-ranked Spaniard 6-7 (5) 7-6 (9) 7-6 (3) in a first-round match.
Del Potro has not played on the tour since the Australian Open last January. He needed right wrist surgery soon after and was sidelined for eight months.
"I feel good for all my match, and finally I won a match after one year," he said.
Del Potro, currently ranked No. 258 in the world, will have a protected ranking of No. 5 heading into next week's Australian Open in Melbourne because of his recovery time on the sidelines.
"It was good tennis before the Australian Open, but I still want to win here. I'm ready to fight again."
Del Potro's next opponent will be Germany's Florian Mayer, who dealt with English wildcard James Ward 7-5, 6-0.
In women's play, French Open champion Francesca Schiavone of Italy, the No. 5 seed, was beaten by Alisa Kleybanova of Russia 6-7 (5), 6-1, 6-2.
Fourth-seeded Australian Samantha Stosur advanced to the second round with a 7-5, 6-4 win over Yanina Wickmayer of Belgium, while seventh-seeded Victoria Azarenka of Belarus beat Ekaterina Makarova of Russia 2-6, 6-2, 6-4 and eighth-seeded Li Na of China defeated Anastasia Rodionova of Australia 6-1, 6-2.
Del Potro, 22, who got wildcard entry into the Sydney tournament, said he was not surprised at how well he stood up to the physical test – playing for three hours and 20 minutes in warm conditions at the Ken Rosewall Arena.
"I worked very hard for two months in Argentina. My coaches trust in my condition and I trust myself, so I'm ready again to play long matches," he said.
"I will see how I feel after [Tuesday], but I have my physical trainer here and my coach. They know how I can be better for my next match."
Del Potro said to beat a highly ranked player such as Lopez has given him renewed confidence heading into the new season after his injury nightmare.
"I'm still feeling like it's a long road to play better," he said.
"[Monday] I beat one top-30 player. If I can play with them, maybe in the future I can play like I did two years ago with the top-10 players."
The Associated Press contributed to this report.