Serena Williams was pushed hard by fifth seed Simona Halep before coming through in three sets to reach the semi-finals of the US Open.
The American six-time champion won a gripping contest 6-2 4-6 6-3 in the Flushing Meadows night session to close in on a 23rd Grand Slam singles title.
Williams, 34, will play Czech 10th seed Karolina Pliskova in the semi-finals at Flushing Meadows (00:00 BST, Friday).
They will be followed by Angelique Kerber against Caroline Wozniacki.
Williams and Kerber are battling for the world number one ranking, with the American knowing that, to hang on to top spot, she must reach the final.
Should the German second seed line up as her opponent on Saturday, Williams will have to beat her to stay on top.