Jo-Wilfried Tsonga was made to work hard in the PTT Thailand Open needing three sets to get past Marco Chiudinelli.

The defending champion fought back from a set down to eventually see off the Swiss qualifier 6-7 (7/9) 6-3 6-4 in two hours and 21 minutes.

Frenchman Tsonga will now face Viktor Troicki in the last four. The Serbian fourth seed had an easier time of things against American John Isner, claiming a 7-6 (7/3) 6-2 victory over the eighth seed.

Gilles Simon also had to battle back from a set down to overcome Evgeny Korolev of Russia, the second-seeded Frenchman eventually prevailing 4-6 6-3 6-4.

His next opponent will be sixth seed Jurgen Melzer, who was a straightforward 6-4 6-2 winner over Andreas Beck in their quarter-final clash.