Zverev had to work hard against Shevchenko in Rio

Alexander Zverev has qualified for the quarter-finals of the ATP 500 tournament in Rio de Janeiro.

He faced Alexander Shevchenko, in a match that proved to be a real battle.

Zverev won 7-6, 7-6 in 2 hours 29 minutes in a match full of twists and turns. In total, there were 6 breaks, and Shevchenko served for the set in the first set.

Despite being broken 3 times, the German came through in two tie-breaks, but is still not reassuring about his level.

In a post-match interview, however, Zverev said he wasn't worried: "If you look at my record on clay, I need time to play well on this surface.

In general, 3 to 4 weeks. So I'm happy with my level."

He will face Francisco Comesana in the quarter-finals.