Rafael Nadal suffers shock defeat to Viktor Troicki in Shanghai

Nadal is seventh in the race to London with eight places at the O2 up for grabs, but this early defeat in Shanghai is a setback to the world number five as he attempts to qualify for the lucrative season-ending event.

The 14-times Grand Slam winner Nadal lost to Grigor Dimitrov in the quarter-finals of the China Open last week, and must wait to see how his main rivals for the O2, Tomas Berdych, Marin Cilic and David Goffin, fare this week.

World number four Kei Nishikori will join the world's top three, Novak Djokovic, Andy Murray and Stanislas Wawrinka, and Milos Raonic in London.

Wawrinka had no such problems in Shanghai in overcoming Britain's Kyle Edmund in the second round.

Aiming for a major scalp, Edmund instead succumbed 6-3 6-4 and had to settle for words of praise from his conqueror as his day's reward.

Wawrinka claimed the only break of the opening set in the eighth game, and then looked set to steam through the second after striking first for a 2-0 lead.

But Edmund, the 21-year-old from Beverley in East Yorkshire, made a fight of the contest by reeling off the next three games, bringing the set back on serve and showing Wawrinka he would need to step up his game again.

The US Open champion rose to the challenge in the ninth game, and then fended off three break points in the next to seal victory with a sliced backhand winner into the corner. Edmund, at full stretch on the forehand, was unable to put the ball back into play.

Wawrinka, who dismissed talk of him being a possible future world number one, said he had been wary about facing Edmund, who entered the world's top 50 this week.

"I saw him play the last few days. This year I've seen he's been playing really well recently," Wawrinka said.

"I was expecting a really tough match because he's improving a lot."

Wawrinka added: "He's a dangerous player.

"I'm really happy with the way I controlled the match more or less with my game. There were a lot of positives for me."

2-Andy Murray (Britain) beat Steve Johnson (U.S.) 6-3 6-2

Viktor Troicki (Serbia) beat 4-Rafael Nadal (Spain) 6-3 7-6(3)

13-Lucas Pouille (France) beat Nicolas Almagro (Spain) 6-4 7-6(10)

Vasek Pospisil (Canada) beat Grigor Dimitrov (Bulgaria) 7-5 7-6(2)

Mischa Zverev (Germany) beat 12-Nick Kyrgios (Australia) 6-3 6-1

11-David Goffin (Belgium) beat Benoit Paire (France) 6-1 7-6(0)

3-Stanislas Wawrinka (Switzerland) beat Kyle Edmund (Britain) 6-3 6-4

5-Milos Raonic (Canada) beat Paolo Lorenzi (Italy) 6-2 6-4

Gilles Simon (France) beat Wu Di (China) 6-2 6-2

Marcel Granollers (Spain) beat 7-Tomas Berdych (Czech Republic) 7-6(4) 7-6(1)

Vasek Pospisil (Canada) beat Grigor Dimitrov (Bulgaria) 7-5 7-6(2)

Mischa Zverev (Germany) beat 12-Nick Kyrgios (Australia) 6-3 6-1

Jack Sock (U.S.) beat Feliciano Lopez (Spain) 6-3 4-6 6-4

15-Roberto Bautista (Spain) beat Taylor Fritz (U.S.) 6-4 6-4