WHAT HAPPENED: Ivo Karlovic, the 6-foot-11 human beanstalk capable of delivering serves at supersonic velocity, didn’t take much time in his first-round match  to have his opponent, Bjorn Fratangelo, throw up his hands in frustration as the Croatian’s cannon sent aces whistling by.

The match, started Tuesday and continued in the middle of the second set Wednesday after a day-long rain delay, featured the normal barrage from Karlovic — but an unwavering and focused counter-attack from U.S. wild card Fratangelo. 

The result was four sets of fast, up-and-down tennis as Karlovic bombed 46 aces and relentlessly charged the net. But it was the American who consistently found windows of space around the Croatian’s outsized wingspan and blistering passing shots earned him his first US Open victory, 7-6, 6-4, 3-6, 7-6.

After ill-timed volley misses from Karlovic and a strong serving performance earned Fratangelo the second set (after squeaking by in the first), Fratangelo seemed buoyed by his two set lead.

He came out sharp in the third, but Karlovic found another level, matching his big serve game with blistering returns that flummoxed Fratangelo.

play video Fratangelo vs. Karlovic

As the pair went to the fourth set on a much sunnier Court 4 Wednesday, it seemed the American was undeterred by the third set loss and might cruise to victory; he broke Karlovic’s serve to take a 3-1 lead.

While Karlovic, the No. 38 player in the world, battled back to force a tiebreak, Fratangelo seemed to have found a beat on the Croatian's serve and he couldn’t keep up with the pace of Fratangelo's returns.

The American amassed a 6-2 tiebreak lead and closed two points later with a vigorous scream as Karlovich sent a ground stroke past the baseline. 

WHY IT MATTERS: Bjorn Fratangelo — yes, he’s named after that Bjorn — showed that his third time at the US Open was the charm. This year is the 24-year-old's third straight year earning a wild card entry, and he managed to match his 2016 second round French Open effort. The win also comes after a difficult year —  the American struggled earlier this year with a viral infection and a knee injury. 

MATCH POINT: Fratangelo marveled a bit at Karlovich’s serve in the beginning of the match — even the ones he missed. In the first game, Karlovic knocked over one of the sticks that holds the net up and, on another first serve, a piece of the court’s monitor popped out after a missed Karlovic rocket struck it. 

“You’re breaking everything, man,” Fratangelo told a smiling Karlovic.