Germany's Alexander Zverev defeated home favourite Fabio Fognini in straight sets in the third round of the Italian Open on Thursday in a match which saw the Italian lose his cool over a line call and fail to recover.

Fognini, who beat world No 1 Andy Murray in the previous round, lost the first set 6-3 and his game deteriorated early in the second set, when the Italian argued with umpire Mohamed Lahyani over a Zverev serve.

Lahyani got out of his chair to check a mark at Fognini's request, but told the Italian to "stop talking" after a disagreement over which mark it was.

Zverev, who turned 20 last month, wrapped up the second set 6-3, and will play either Tomas Berdych or Canada's Milos Raonic, the No 5 seed, in the quarterfinals.