Del Porto, Wawrinka through to Basel Open Quarters

Top-seeded Stan Wawrinka opens Tuesday against fellow Swiss Marco Chiudinelli. "I tried to play with confidence even on my second serve. In the second set I was playing much better tennis".

"My goal now is only as far as the next round, I'll try to keep my level up in the quarterfinals".

Cilic now stands provisional ninth for the eight-man field at the Tour Finals after passing Tomas Berdych in the table. Croatia's Marin Cilic celebrates after wining the final match against Japan's Kei Nishikori at the Swiss Indoors tennis tournament at the St. Jakobshalle in Basel, Switzerland, Sunday, Oct. 30, 2016.

The Argentinian had not dropped a set to Nishikori in their previous four meetings but the world number five claimed a solitary break in either set to advance courtesy of a 7-5 6-4 victory.

The Japanese, who will also be in Paris, was playing his fifth final of the season - but can boast only the Memphis title from February.

Del Potro beat Roger Federer in the 2012 and 2013 finals in Basle.

"I'm looking forward to the final". His game has improved a lot.

Zverev hung on for one of the biggest wins of his career, booking his spot in the semi-finals.

"It's tough to think of the past, but when I remember that match it gives me some guidance about how to play this next one", Cilic said. "My game has changed since my (wrist) injury but if I serve well, I have a chance to win".

American eighth seed Jack Sock eliminated Frenchman Adrian Mannarino 6-3, 6-3 while Moscow champion Pablo Carreno Busta won an all-Spanish showdown over Fernando Verdasco, 7-5, 6-3.

Nishikori dealt out only seven aces, but fired his last one to earn a pair of match points - one was enough as he put away a volley victor at the net.

Results on the fourth day of the Swiss ATP Indoors on Thursday (x denotes seeded player).

  • Julie Sanders