Nine-time champion Federer into 15th Swiss Indoors final

Roger Federer is into his 15th Basel final AFP/FABRICE COFFRINI

The top seed will be playing for his 10th title at his home tournament when he faces Alex de Minaur in a first-time meeting after the Australian stopped Reilly Opelka 7-6 (7/2), 6-7 (4/7), 7-6 (7/3).

Federer, 38, has now made the Basel final in his last 13 appearances and 15th overall.

His last defeat came in the 2013 final at the hands of Juan Martin del Potro.

For Federer, victory on Saturday was his second of the season over 21-year-old Tsitsipas who had stunned the 20-time major winner at the Australian Open in January.

Federer, who had a walkover in the quarter-finals due to the pre-match injury withdrawal of compatriot Stan Wawrinka, notched up two love games in the second set and advanced on his first match point.

"Having the crowd behind you really helps you believe in your game," said Federer who had also defeated Tsitsipas in Dubai earlier this year.

"I had to play aggressive and take risks against Stefanos. There was a lot of running. But it's always easier to play at home, I was energised."

Federer will be in uncharted territory in the final with De Minaur, who has won trophies this season in Sydney, Atlanta and Zhuhai.

"He's one of the fastest players," Federer said. "I'm very excited to be in the final again.

"I was not sure how it would go this week, so I'm really happy."

The 28th-ranked De Minaur, who trains and lives in Spain, is the first Australian to reach the Basel final since Mark Philippoussis finished runner-up in 1997.

De Minaur, who measures up at 1.80m compared to Opelka's towering 2.11m, set up his semi-final victory with a passing winner for four match points.

Opelka saved the first with an ace but was caught out on the second as his opponent sealed the win.

"Nothing can prepare you for that serve," de Minaur said.

"Reilly's an incredibly tough competitor who never gives up. I'm just happy to be in the final. I guessed right a few times and got lucky. I was just lucky to have gone the right direction, I was just hoping not be hit by any of those serves."