Eighteen-year-old Reilly Opelka gets the John Isner comparison a lot. It’s an understandable one, as the Palm Coast, Florida, native stands at 6-foot-11, making him one of the few able to stand face-to-face with Isner. He also boasts a powerful serve, albeit not quite as developed as Isner’s trademark.

Opelka will get to see how he measures up with Isner on the court Saturday when the two face off in the BB&T Atlanta Open’s semifinals.

“I know what to expect,” Opelka said. “John’s probably got the best serve of all time. John’s going to hit a lot of dingers. (He’s a) big friend with a big serve.”

Opelka said there’s more to he and Isner than just similar heights. He said the 31-year-old Isner has been a role model and that he really admires Isner’s tenacity on the court. There’s no chance to count out Isner until any given match is over; opponents who thought they could do so often walked away with a loss.

Opelka’s admiration for Isner speaks to the stage of Isner’s career today. Now in his 10th year in the professional ranks, Isner will continue to be cited by the young up-and-comers as a hero.

“I’m starting to hear it a little bit now,” Isner said. “I’ve answered that question on Reilly’s side before with guys I’ve looked up to like Andy (Roddick), James (Blake), Mardy (Fish). For guys to say that now is pretty cool and pretty humbling.”

Isner praised Opelka, who he said reminds him of himself at that age but even better.

Opelka has accomplished a lot to even reach Isner, as he’s won three matches in only his third ATP World Tour tournament. He beat reigning ACC Player of the Year Christopher Eubanks 7-6, 7-6 in the opening round then pulled off one of the week’s biggest upsets, knocking off No. 29 Kevin Anderson 6-7 (5), 6-3, 75. He followed that up by beating Atlanta’s Donald Young in straight sets.

The surge this week will move Opelka from No. 837 in the ATP rankings to somewhere around 387.

“It’s interesting,” Opelka said. “I never made semifinals in Futures. I never won a match in Challenger; part of that was because I didn’t play many.”

Part of Opelka’s recent triumphs can be attributed to his health. He said he finally got over a lingering right foot injury about three weeks ago after it slowed him down for close to eight months. Even when it wasn’t an issue, he said it was always in the back of his mind.

When it comes to the showdown with Isner, Opelka sounded up to the challenge. He said he has no goals or expectations to close this tournament, only to keep it simple and try to pile up points and games.

Knowing what he knows about Isner, it’s safe to say Opelka understands the challenge he’ll face on Saturday afternoon. That said, don’t expect him to flinch while trying to take down the top-ranked American.

“I have a lot of belief in my game,” Opelka said. “If I serve well, hit my (forehand) well and return well, I can hang with anyone.”