Swiss Indoors: Wawrinka pulls out of Federer quarterfinal with back injury

Roger Federer will not face the familiar foe of Stan Wawrinka as planned after the latter withdrew from the Swiss Indoor Basel due to a back injury.

Stan Wawrinka, who was set to take on countryman Roger Federer in a last-eight game, withdrew in Basel.

Stan Wawrinka has been forced to pull out of a dream home quarterfinal against Roger Federer at the Swiss Indoors Basel due to a back injury.

The seventh seed Wawrinka displayed plenty of grit to dispatch of Frances Tiafoe 6-3 3-6 7-5 on Thursday and was set to meet Swiss great Federer in the last-eight.

READ| Swiss Indoors Basel 2019: Tsitsipas in quarterfinal

However, Wawrinka – a losing finalist to Andy Murray at last week's European Open – will not be able to take to the court to face Federer for a 27th time.

"The bad news is that I will have to retire," he said.

"I had some trouble with my back in the last game. I'm sure I cannot make it for tomorrow [Friday]. I will pull out."

Third seed Stefanos Tsitsipas had to fight back to avoid an upset against Ricardas Berankis, the Greek recovering to seal a 6-7 (4-7) 6-2 6-4 triumph. 

Filip Krajinovic is up next after he upset fifth seed Fabio Fognini 6-2 6-4, while Roberto Bautista Agut needed three sets to defeat Richard Gasquet.

Reilly Opelka will take on the Spanish fourth seed after he recovered from a set down to defeat David Goffin 6-7 (4-7) 7-6 (7-4) 7-5.