Alexander Zverev booked his place in the Hamburg Open semi-finals with a straight-sets victory over Zhizhen Zhang.

The top seed - and reigning champion - kept his title defence very much on track, prevailing 6-4 6-3 after 66 minutes on Center Court.

Zverev dominated on serve during the opening set, dropping just three points, while a break in game five paved the way for him to move halfway towards victory.

The home favourite made another statement of intent when he broke in the opening game of the second set.

Another break followed at 5-3 to secure victory and send the Italian Open champion through to his seventh ATP semi-final of the season - and third on clay, having also reached the French Open final.

There, he will play Pedro Martinez after the Spaniard beat fourth seed Francisco Cerundolo in three sets.

Data Debrief: Statement of intent from Zverev

The German demonstrated his desire to maintain his hold on the trophy he won in front of his home crowd last season, and become only the third player this century to successfully defend the crown after Roger Federer and Nikoloz Basilashvili.

Indeed, Zverev hit 10 aces and won 29 of 33 points on first serve (88%), while converting three of his four break-point opportunities.