(Reuters) - Frenchman Jo-Wilfried Tsonga became the first high-profile casualty in the men's event at the U.S. Open when he was upended 6-4 1-6 6-1 6-3 by Slovakian Martin Klizan in the second round on Thursday.

The fifth seed produced a strangely lackluster display as he was outplayed by the world number 52 and suffered his earliest-ever U.S. Open exit.

The left-handed Klizan had never been beyond the second round at a grand slam event before but he surprised Tsonga with some inspired tennis.

Tsonga rallied from 4-1 down in the fourth set to 4-3 but the 23-year-old Klizan held his nerve to seal the biggest victory of his career.