HONG KONG - Top seed and defending champion Andrey Rublev of Russia suffered a surprising defeat to Hungary's Fabian Marozsan in the second round of the ATP Hong Kong Open on Thursday.

The world No 8 fell to 58th-ranked Marozsan 5-7, 6-3, 3-6 after a match that lasted one hour and 58 minutes at Victoria Park.

Marozsan will face China's Shang Juncheng in the quarterfinals. Shang, 19, advanced comfortably, defeating seventh seed Pedro Martinez of Spain 6-3, 6-1.

In the day's other action, second seed Lorenzo Musetti of Italy triumphed over qualifier Gabriel Diallo of Canada, while Spain's Jaume Munar upset fifth seed Nuno Borges of Portugal 6-3, 7-5.