Dominic Thiem Suffers Blow to ATP World Tour Finals Hopes

Dominic Thiem faces an anxious wait to see if he qualifies for the ATP World Tour Finals after slumping to a 6-2, 6-4 defeat against Jack Sock at the Paris Masters on Wednesday.

Thiem entered this week's tournament occupying one of the final two qualifying spots for London, but his second-round exit has left his place in the eight-man field vulnerable.

The Austrian dropped his opening service game against Sock, setting the tone for a dismal afternoon as the American blew away the sixth seed in under an hour.

Thiem has won four titles this season and reached the semi-finals of the French Open, but his subsequent dip in form could prove costly with six players still fighting for the remaining two London berths.

Marin Cilic, a winner in Basel at the weekend, further bolstered his chances of playing at the November 13-20 Tour finals by defeating compatriot Ivo Karlovic 7-6 (9/7), 6-2.

With Rafael Nadal calling an early end to his season, the Croat is eighth in the Race to London standings and will face David Goffin for a place in the quarter-finals.

Belgian Goffin is still in the hunt after beating Nicolas Mahut 7-6 (9/7), 6-2, while 2008 Paris champion Jo-Wilfried Tsonga cruised past Albert Ramos-Vinolas 6-3, 6-4.

French 13th seed Lucas Pouille is out of the running, though, despite rallying to beat Feliciano Lopez 6-7 (1/7), 6-3, 6-4.

Pouille had arrived in the French capital with very slim qualification hopes but Cilic's earlier victory eliminated him from contention.

Japanese fifth seed Kei Nishikori collected his 300th career win by knocking off Serbia's Viktor Troicki 6-2, 7-5 to take his place in the last 16.

"I think it's a great number," said Nishikori.

"I'm not sure if it's good or not. I don't know how good that is, but, you know, just try to get one win every match, and just play one match at a time."