Thousands of fans were still streaming up the escalators, along the concourses and toward their seats inside Arthur Ashe Stadium when a public service announcement went out.AMEX wanted to offer two fans a free upgrade – the chance to come down from the nosebleeds and watch two of tennis’ brightest stars up close.There was only one problem: after just 27 minutes of this fourth-round clash, Coco Gauff was already racing toward the US Open quarterfinals. The No 4 seed had climbed aboard her own American Express and, in the rearview mirror, poor Iva Jovic was shrinking by the second.So much for the mouthwatering tussle we had dreamed of. Jovic, only 18 but already ranked No 14 in the world, was being given a brutal lesson by Gauff, the 2023 champion and elder stateswoman at the ripe old age of 22.After Gauff sealed the first set in barely half an hour, it appeared this match would be over by the time that lucky couple had settled into their expensive seats.Instead, Jovic showed some of the grit and stylish shot-making that has carried her to the cusp of the world’s top 10 barely a year after stepping up from the juniors full-time. She clung on to Gauff for another hour before finally succumbing 6-1 6-4. There is no shame in that – this was her first trip to the fourth round. It won’t be her last. Coco Gauff beat teenage rival Iva Jovic in an all-American US Open showdown on Monday Jovic, who is only 18 but already ranked No 14 in the world, was beaten 6-1 6-4 Gauff, the 2023 champion and elder stateswoman at 22, will now face Mirra AndreevaAs for Gauff? The 2023 champion marches on to the last eight, where she will fancy her chances of securing a second US Open title in four years. First up, though? Another teenage sensation stands in her way: Mirra Andreeva, the 19-year-old French Open champion.’Iva is an incredible player, an incredible talent,’ Gauff said. ‘She plays beyond her years and I’ve been in a similar position as her so I’m looking forward to many more battles out here. I’m sure we’ll be playing a lot more matches in the future.’ Two years ago, Jovic’s US Open debut ended in the shadow of this vast arena. In searing temperatures out on Court 12, in a second-round showdown with Ekaterina Alexandrova, the American – then just 16 – was beaten by the elements as much as by her opponent.Medics rushed on to court as Jovic burned under the New York sun. They checked her blood pressure and her pulse. Early on Monday evening, under the bright lights of Arthur Ashe, there was little evidence that Jovic would wilt once more.She raced out the blocks, winning the opening arm wrestles to break Gauff at the first opportunity.Before long, however, Jovic was threatening to implode. Gauff won six straight games in just 30 minutes to take the first set 6-1. The No 4 seed had one foot in the quarterfinals.Jovic did not win a service game until the opening game of the second set. It was sealed with a tremendous backhand passing shot and the teenager marked this small mercy by bending at the waist and pumping her fist.But to keep her US Open dreams alive, Jovic needed to do more than stop the bleeding. And to her credit, the 18-year-old began to land some blows of her own. Inside Arthur Ashe, the noise levels ratcheted up as a tug of war broke out, dragging both players around the court. Jovic, who turns 19 in December, did not win a service game until the opening game of set two Gauff is now just three victories away from winning her second US Open title Join the discussionIs rising talent like Jovic making it tougher for Gauff to keep her US Open crown?What’s your view?Alas, even as Jovic grew into this match, Gauff refused to budge. The No 4 seed put a finger to her ear after winning one titanic rally. She then broke serve. Jovic responded immediately, only for Gauff to regain her advantage and then seal her spot in the quarterfinals. Jovic rushed off court but the teenager will be back on Arthur Ashe before too long. This was a breakout year that saw her reach the fourth round at Wimbledon and the Australian Open quarterfinals. Gauff knows better than most about the challenges of turning teenage promise into major titles. Four years separated her historic win over Venus Williams at Wimbledon and a first major triumph in New York. She was 19 by then. In each of the past two years, Gauff’s hopes of landing another US Open title were dashed in the fourth round. This time, she stepped over that hurdle. The 22-year-old has reached the quarterfinals without dropping a set. Andreeva, who edged past Anastasia Potapova on Monday, will hope to end that streak. No easy task when Gauff plays like this. When she continues to make history – with this win, the 22-year-old is now the youngest American woman to reach three Grand Slam quarterfinals in a calendar year since Serena Williams in 2003.