Coco Gauff sinks Aryna Sabalenka to set up WTA Finals showdown with Zheng

• American outlasts world No 1 7-6 (4), 6-3 in Riyadh
• Zheng Qinwen beats Barbora Krejcikova in first semi

When Coco Gauff and Aryna Sabalenka stared each other down just a month ago in Wuhan, Gauff clearly had the edge as she methodically established a set and break lead. But then, out of nowhere, her serve spectacularly crumbled. Although she fought brilliantly until the end, she was torpedoed by an astounding 21 double faults.

Having already been a presence on the tour for half a decade, it is sometimes easy to forget that, at 20 years old, Gauff is still growing, still a work in progress. Throughout this week, Gauff has shown the results of some of that progress as she arrived in Riyadh with significant adjustments in her game and she has used them to play some of the best tennis of her career. On Friday, Gauff produced a brilliant performance against Sabalenka, the world No 1, to reach the final of the WTA Finals with a spectacular 7-6 (4), 6-3 win.