Kei Nishikori and Stan Wawrinka each survived significant scares as they battled through to the semi-finals of the Geneva Open on Thursday.

Second seed Nishikori dropped the first set to Kevin Anderson and then saved three match points in a decisive tie-break before triumphing 2-6 6-4 7-6 (8-6).

"There haven't been too many times that I'm down match point and win, so it’s great for me," said the Japanese.

"He had more chances, but I served a little bit better in the end. It’s important to win some matches like this."

Next up for Nishikori is a last-four tie against qualifier Mischa Zverev, whose good form continued with a 6-4 7-5 win over fifth seed Steve Johnson.

Defending champion Wawrinka, meanwhile, came from a set and a break down to beat Sam Querrey 4-6 7-5 6-2.

The Swiss will now face Andrey Kuznetsov, who beat lucky loser Cedrik-Marcel Stebe in three sets.