Sock, currently ranked 18th in the world, claimed a 6-3, 2-6, 6-2 win over Nishikori, ranked fifth, at the Indian Wells Tennis Garden.

After today's win, Sock will now meet Roger Federer of Switzerland in the semi-finals, who he lost to in straight sets in the fourth round of the 2015 tournament.

Australia's Nick Kyrgios was forced to withdraw from his quarter-final against Federer after suffering form food poisoning.

The 21-year-old, seeded 15th, beat world number two Novak Djokovic in the previous round, but failed to take to the court today.

"After a restless night of being sick I have nothing left and to play a great champion like Roger, I need to be at my best to have a chance," Kyrgios said in a statement.

"I don't take this decision lightly, these are the matches we train for but I'm in no fit state to take to the court.

"I'm sorry to the fans but I have to put my health first and I hope you understand."

In the women's singles competition, Russia's Elena Vesnina comfortably defeated Kristina Mladenovic of France 6-3, 6-4 to reach tomorrow's final.

“It got tight at the end because Kristina started to play so free,” said Vesnina, who defeated American Venus Williams 6-2, 4-6, 6-3 in the last eight.

“She started to put a lot of pressure on me.

"It’s tough to play the whole match like this, so i tried to play steady.

"I tried to focus point by point.”

She will now take on her compatriot Svetlana Kuznetsova in the final.

Kuznetsova, who last reached the Indian Wells final in 2008, defeated the Czech Reublic's third seed Karolina Pliskova 7-6, 7-6.