American sixth seed Coco Gauff has bolstered her hopes of securing a maiden grand slam title with a stress-free 6-0 6-2 win over Latvia's Jelena Ostapenko to reach the US Open semi-finals.
The 19-year-old becomes the youngest American to reach the tournament's last four since serial champion Serena Williams in 2001.
Gauff, whose lead-up to the US Open included hardcourt titles in Washington and Cincinnati, converted six of her seven break points and dropped serve just once during a steamy 67-minute match at Arthur Ashe Stadium where the temperature rose above 32C.
"It feels great, so happy," Gauff said during her on-court interview on Tuesday.
"Last year I lost in the quarter-final stage and I wanted to do better this year.
"I am happy and ready to get back to work for the next one."
Ostapenko entered the match full of confidence having upset world No.1 Iga Swiatek in the previous round but against Gauff the misfiring Latvian 20th seed could not find her range and delivered an error-filled performance.
Gauff was in control from the start and showcased excellent court coverage while delivering a steady stream of balls deep into the corners en route to capturing the first set in 20 minutes and limiting Ostapenko to seven points.
Former French Open champion Ostapenko finally got on the board with a break to level the second set at 1-1 but Gauff broke straight back for a 2-1 lead with a backhand crosscourt winner.
Ostapenko held serve for the first time 49 minutes into the match but her 19-year-old opponent went up a double break for a 5-2 lead before closing out the encounter on her serve.
Gauff - who was left in tears when she lost to the Latvian in the last 16 at this year's Australian Open - had just 14 unforced errors to Ostapenko's 36.
Her last-four opponent will be 10th seed Karolina Muchova, who overwhelmed Romania's Sorana Cirstea 6-0 6-3.
Muchova smacked 32 winners and played outstanding defence to see off the 33-year-old Cirstea and reach her first US Open semi.
"Unbelievable. It's a really sweet victory and this stadium, I mean, incredible," Muchova said.
The Czech knows she will be up against a feverish home crowd, as well as the in-form Gauff in Friday's semi-final.
"She's an amazing player and she has the home crowd here," she said.
"It's going to be very tough but I want to enjoy this win and then I'll try to put up a battle against Coco."
