Roger Federer is through to the semi-finals in Basel for the 15th time in his career after his compatriot Stan Wawrinka withdrew from a hotly-anticipated clash on home soil.
Federer, chasing a 10th title at the Swiss Indoors, was due to meet Wawrinka, 34, for the 27th time but the world No. 17 worse a back issue in a 6-3 3-6 7-5 win over American Frances Tiafoe.
‘I had some trouble with my back in the last game,’ said Wawrinka. ‘I’m sure I cannot make it for tomorrow (Friday). I will pull out.’
Federer has only lost once at the semi-final stage – to Argentina’s David Nalbandian in 2002 – and will face either Stefanos Tsitsipas or Filip Krajinovic on Saturday. Should Federer reach the final, he will scale above Daniil Medvedev into third position in the Race To London – the rankings system that only takes into account results in a calendar year.
Reilly Opelka will face Roberto Bautista Agut, while Jan-Lennard Struff takes on Alex de Minaur in the other quarter-final matches on Friday.
And Federer's Swiss compatriot Wawrinka insisted he has to take care of his body as a gruelling year reaches its final tournaments.
“The disappointment is huge,” admitted Wawrinka.
"Not to be able to play this match in Switzerland is very sad. But I need to listen to my body at this point.”
It comes after he defeated Radu Albot in the second round with Federer only dropping six games all tournament so far.
Federer is chasing for his tenth Swiss Indoors title and has his family supporting him in his home country but it's not worrying the superstar.
"I’m quite confident and comfortable on the court," he said. “Maybe in the beginning when I got to my first semis or finals and was trying to get over the first hurdle.
“Yes, I was feeling some pressure and it was always the hardest to play in front of my friends and family here in Basel but not the last 17 years.
“I’ve really enjoyed every moment and I’ve always tried to understand how I should take advantage of the fact that I’m playing at home and have home court.”
