PARIS -- Sixteen years ago, a spidery 24-year-old from Zagreb, Croatia, stunned top-ranked Lleyton Hewitt, who was trying to defend his Wimbledon title, in the first round.

It was the first (and last) time that happened at any event in the Open era and the unlikely career of Ivo Karlovic was properly launched. He was 6-feet-11 and, from that lofty perspective, he hit serves you could barely see.

Last year, Karlovic was still a serviceable player, ranked No. 23 at year's end, with his sixth title, at Delray Beach. That victory, at the age of 36, made him the oldest ATP World Tour champion since Jimmy Connors won at Tel Aviv in 1989.

Ivo Karlovic socked 41 aces in a five-set win Wednesday at the French Open. Dennis Grombkowski/Getty Images

Wednesday at Roland Garros, Karlovic joined Connors in another soon-to-be-AARP-sponsored milestone: Karlovic reached the third round of this French Open with a monumental 6-7 (2), 6-3, 7-6 (3), 6-7 (4), 12-10 victory against Australian wild card Jordan Thompson. In doing so, Karlovic, now 37, became the oldest man to reach the third round of Grand Slam since Connors mesmerized the tennis world at the 1991 US Open.

"It's the only time when being old is OK," Karlovic said later while smiling. "So, yeah, I like."

Appropriately, this is the 25-year anniversary of Connor's blazing run to the semifinals at the age of 39.

And it was how the No. 27-seeded Karlovic did it that was so impressive.

The match required 4 hours, 31 minutes, and Karlovic cranked out no fewer than 41 aces. He hit a scintillating 103 winners. Old people sometimes fade when they exert themselves, but Karlovic grew stronger than his 22-year-old opponent. In the ultimate set -- which ran 86 minutes alone -- he produced nine aces and zero double faults, 27 winners and only eight unforced errors.

"Yeah, it's unbelievable because this year I was struggling with the injury with the knee," Karlovic said. "So I was out for two months almost. So this is really unbelievable for me."

Maybe they'll be showing highlights from this match 25 years from now during tennis rain delays on Croatian television.

It's all a part of the ATP's gray movement. Karlovic is one of a record 51 men in the tournament who is 30 years or older.

Karlovic came into Roland Garros with a less-than-spectacular 4-10 career record here; this is only the second time he's reached the third round. This year has been difficult for him, too. Karlovic, nursing a knee injury, had won only two of 11 matches.

Those 41 aces? Those are the second-most he's hit at Roland Garros, where the thick red clay blunts his power. In 2009, he hit 55 in a second-round match -- yes, against Hewitt. In his news conference, he actually cited that number -- without notes.

Karlovic, the all-time leader in career aces with more than 10,600, will look to reach the fourth round at Roland Garros for the first time Friday. This from a player who was understandably thought of as a future basketball star growing up.

Drazen Petrovic and Dino Radja are products of the Croatia, so how did Karlovic manage to avoid playing the sport so obvious for one so tall?

"I don't know. I don't know," he said. "That is what I ask of me every day. Why? Why? No, I'm joking. I remember when I was maybe 13 years old I was practicing basketball, and they really liked me, but I didn't like.

"But now, when I look back, [basketball] would be easier, easier, a lot. In tennis it's really unbelievable, but it was long and hard journey."