Bernard Tomic, a player who before he was a teenager was expected to win Grand Slam titles, sank to the ground as if he had just won one. Tomic, a 21-year-old former prodigy from Australia, had just won the second title of his career on Sunday, beating the defending champion Ivo Karlovic, 7-6 (5), 3-6, 7-6 (4), at the ATP Claro Open Colombia in Bogotá.

“It was a lot of emotions throughout the tournament, especially the last match and last point,“ Tomic said by telephone after the final.

Tomic had asked for a wild-card entry into Bogotá after a second-round loss at Wimbledon dropped his ranking to 124th, his first time outside of the top 100 in three years. With the title, he rebounded to 70th. “I wasn’t expecting to win,” he said. “I gathered as much as I could; I prepared as best as I could for the tournament, and at the end, it just shows you: If you believe and you prepare the best that you can, then you have a lot of chances to win.”

Tomic was emotional throughout his run, throwing his whole body into exultant fist pumps and frequently crossing himself before important points, uncharacteristic behavior from a normally relaxed player. His casual demeanor during losses had frequently led to assertions by observers that he was giving less than a full effort, even earning him the derisive nickname Tomic the Tank Engine.

One of his most questionable efforts came in March, when Tomic lost, 6-0, 6-1, to Jarkko Nieminen in Key Biscayne, Fla. At 28 minutes 20 seconds, it was the shortest completed match in ATP history.

Indeed, when Tomic recounted his road back from bilateral hip surgery in January, he omitted his appearance in Florida, saying that he had started his comeback in May in Madrid.

“Look, tennis is a funny sport,” Tomic said of the perceptions of his level of effort. “I always try to do my best and play as best as I can. Some days on court, you just don’t feel it; the other players are playing too good. It’s not always going to go your way. Obviously, you want to try to avoid that feeling, and you want to put in as much as you can, and I think this tournament, I was giving everything I had in my heart.

“That’s, I think, one of the reasons why I was so focused throughout this tournament, and it led me to win this title. And in the future, for me, the big thing is working hard and continuing to improve my game. Then I’m going to have more shots at these tournaments and titles to win.”

Tomic’s reputation has taken such a hit that even his 16-year-old sister, Sara, is sometimes heckled at her junior tournaments because of how Tomic is perceived.

“I do get a lot of hatred just because my brother, they get the wrong image of him,” Sara Tomic told The Gold Coast Bulletin in Australia last week.

A title for Tomic this week would have been particularly difficult to predict recently, as his longtime management company, IMG, announced last week that it was terminating its relationship with him before their contract ended.

“We — myself, my father and my team — decided to leave IMG,” Tomic said of the split, which both sides said was a mutual decision.

Tomic said he was now looking forward to a measure of greater independence. “Just to be for myself,” he said. “I was booked in an agency pretty much all my life, and at a company that was so big, like IMG.”

Because of his early appearance on the tennis radar and the frequent criticism that he has not fulfilled his potential, Tomic sometimes has difficulty remembering he is still only 21, making him one of the youngest players in the ATP top 100 and the youngest on tour to have won an ATP title, much less two.