World number one Aryna Sabalenka survived her toughest test of the tournament to beat Wimbledon champion Linda Noskova 7-6 (1), 3-6 7-6 (10-7) on Tuesday and reach the US Open semi-finals for a sixth consecutive year.
Defending champion Sabalenka had not dropped a set before facing the Czech sixth seed, who fired 18 aces and saved seven of nine break points but faltered when leading by a break in the final set.
Sabalenka next plays the winner of an all-American clash between Jessica Pegula and Emma Navarro.
The Belarusian broke in the second game, whipping a forehand into the corner that Noskova did not even attempt to chase down, but the Czech broke back with a pair of powerful groundstrokes from the baseline in the ninth.
Sabalenka sprinted through the opening set tiebreak before a double fault gave Noskova a 4-2 lead in the second set. She screamed in frustration when a pair of double faults midway through the third helped her opponent secure another break.
Sabalenka recovered to level in the eighth game, however, and was in her element in the decisive tiebreak, where she clinched it with an ace.
