Rafael Nadal clenched his fists and roared at the U.S. Open on Monday.

He had just broken Frances Tiafoe’s serve to take a 3-1 lead in the fourth set, reclaiming the momentum against an inspired, much younger American opponent who had cracked before with a major upset in reach.

It looked, from long and recent experience, as if Nadal was teeing up another comeback victory in a career defined by in-the-moment grit.

But a strange thing happened on the way to another revival. Nadal lost his serve and his way in the next game under the closed roof of Arthur Ashe Stadium, and though he still scrapped and whipped his trademark topspin forehand, he was ultimately unable to avoid an unpleasant fourth-round surprise.