​NEW YORK — Coco Gauff is not messing around. After a scratchy third-round win Saturday, Gauff came to the U.S. Open on Monday night to play.Under the lights in Arthur Ashe Stadium, Gauff was the wizened veteran taking on the new American prodigy, Iva Jović, who was 48 hours removed from a magical three-set, three-hour win over her close friend Alex Eala.The match, and their embrace at the end, captivated the tournament.Gauff doesn’t have much time for tennis sentimentality these days. She has spent the past year breaking down and rebuilding the two most important shots in her game with the sole goal of winning a third Grand Slam title, and many more after that.On Monday night, she took another big step in that direction against a player who seemed on the cusp of causing her some trouble. Jović didn’t do much of that early, but then she did, bending but not breaking, hanging under near-relentless pressure from the woman playing arguably the best tennis right now.When it was over, Gauff was into the quarterfinals for the third time in four Grand Slams this year with a 6-1, 6-4 win that served as another message to the rest of the field.She also had a message for Jović.“Incredible player and incredible talent,” Gauff said in her on-court interview.“Give it up for Iva … There was one game when I felt like I was running a marathon. First time I was out of breath on court in a long time.”It hadn’t looked like it was going to go that way.At one point early in the second set, Gauff had won twice as many points as Jović. By the end, she had 65 and Jović had 44. But just two or three of those points, in the middle of the second set, showed why Gauff asked the crowd for praise for her opponent — after she had vanquished her.Jović was getting her teeth back into the match, showcasing her controlled aggressiveness. She could hang with Gauff for long enough to find an opening in a rally, and then she could put the ball right through it.Then, she went to showcase some of her deft touch at the net. Jović half-volleyed two drop shots that most players wouldn’t have bothered chasing after.Gauff caught up with both of them. Of course she did.On one of them, she also somehow then chased down Jović’s attempt to knock her slice into the open court. Jović looked up, saw Gauff was there, and raised the white flag.Gauff knocked the ball into a rectangular expanse of blue, as Jović stood in the doubles alley and doubled over to her knees, trying catch her breath.Gauff finished the business in a manageable 93 minutes, but Jović pushed her to the end. Gauff was down 0-30 as she tried to serve out the match. She attacked with a backhand. She got Jović to miss a soft, kicking serve.Then she got lucky, when her overhead hit the top of the net and bounced through the court to bring up match point.She served-and-volleyed her way across the finish line, hugged Jović and let out a scream.This article originally appeared in The Athletic.Tennis,