World No 2 Alexander Zverev was knocked out of the Madrid Open in the round of 16 by Argentina's Francisco Cerundolo on Tuesday as defending women's champion Iga Swiatek had a few scares before advancing to the quarter-finals. Cerundolo, ranked 21, beat the German -- a two-time former winner in Madrid -- 7-5, 6-3 to repeat his feat from last year.

Zverev lost his temper, took his phone and took a picture of a questionable call. Mohamed Lahyani could not do anything about it, and he gave the German a code violation warning. Alexander kept his composure and clinched the set in the tie break before prevailing in the decider.