INDIAN WELLS, Calif. — It was 2011. Ivo Karlovic was already an ATP Tour veteran with graying temples, and his close friend and former coach Tarik Benhabiles was talking about Karlovic’s serve, and his future.

“He has a huge weapon,” Benhabiles told me. “He can play until he’s 40 years old, no problem.”

Kudos to Benhabiles, who once helped Andy Roddick become a force, for knowing his tennis. But, above all, kudos to Karlovic, the 6-foot-11 Croatian, for finding a way to fight and serve through everything life has thrown at him.

It has hardly been “no problem,” but Karlovic turned 40 on Feb. 28, and he is definitely still playing.

He has won three rounds at the BNP Paribas Open this year and is now the oldest man to win a singles match at a Masters 1000 event. On Wednesday, with plenty of gray in his beard now as well as in his temples, Karlovic will deploy his fearsome weapon against Dominic Thiem, the No. 7 seed, for a place in the quarterfinals.