Despite multiple attempts, Zverev hardly closed the gap on No. 1 Jannik Sinner, who has barred from tennis competition since February.

Alexander Zverev's third-round match became controversial when he photographed a disputed ball mark, reigniting debates over electronic line-calling.

Iga Swiatek advanced to the quarterfinals of the Madrid Open after a "more relaxed" day following a blackout while top-seeded Alexander Zverev was upset by Francisco Cerundolo.