Serena Williams survived a severe test of her credentials against the hard-hitting Kaia Kanepi on Sunday as she advanced to the quarter-finals of the US Open with a 6-0 4-6 6-3 win.
The American dropped a set for the first time in the tournament as Kanepi – a two-time quarter-finalist in these parts – bounced back from a horrific start.
Kanepi won just six points in the opening set as Williams laid down a marker, but she fought back and used her own ferocious power to blast through the six-time champion.
Unmoved by her opponents revival, Williams regained her composure to set up a last-eight tie with the Czech Republics Karolina Pliskova.
Pliskova – a former world No. 1 and 2016 runner-up at Flushing Meadows – had earlier defeated Australias Ash Barty in straight sets.
Serena came out all guns blazing.
The American sent 14 winners whizzing past the Estonian and only made two unforced errors on her way to bagelling her opponent in 18 minutes.
There were fears that the match would be over in a flash, but Kanepi put her finger on the reset button and flew out the traps in the second set, breaking on her way to a 2-0 lead.
A second break followed, with Serena stunned and the world No. 44 moved to within one game of levelling the match at 5-2.
Getting noticeably louder, Williams stole one of the breaks back and began to mount the pressure on the world No. 44.
But Kanepi held firm and took the 23-time Grand Slam champion into a decider.
As in the first, Williams broke early on and although Kanepi kept within touching distance, the home favourite powered her way into the final eight.