"Obviously (del Potro) has everything to win and nothing to lose", said Wilander, who is at the US Open as analyst for Eurosport. Thiem's second serve was initially called good, but del Potro challenged, and the review showed the serve was out, ending the match.
With Federer 36 and Nadal 31, the future remains very uncertain, but if they do finally meet here in NY, it will be not only a duel for a place in the final but a duel for the No. 1 ranking, now held by Nadal.
He raced to a 4-0 lead in the second as Del Potro looked completely out of sorts.
Vandeweghe, having conquered her fear of majors, is inching ever closer to the head of the gifted USA women hoping to crack the Grand Slam code.