Federer overcame an early break in the first set to notch a 6-3, 7-5 victory over Jan-Lennard Struff. He'll face Gilles Simon next.
BASEL, Switzerland — Roger Federer made it 17 wins in a row at the Swiss Indoors when he defeated Jan-Lennard Struff of Germany 6-3, 7-5 on Thursday to march into the quarterfinals.
The top-seeded Swiss, who was born in Basel, had his serve broken in the third game, but he fought back well by winning five consecutive games to stay on course to reach the final for the 14th time.
The 37-year-old Federer next meets Gilles Simon of France, who knocked out Ernests Gulbis of Latvia 7-6 (4), 7-6 (0).
''I was ready for Struff to come out and swing,'' Federer said. ''I didn't know how aggressive he was going to play, or how much serve and volley he was going to do. But, unfortunately, I didn't have the best first two service games.
''He connected well, he came out with a plan and it worked for him. In the second set it was close throughout, but I think I was able to clean up my game a little bit. I'm happy I improved after a rocky, slow start today, to play well after that. I think the crowd was really into it. They were excited I came back from being a break down.''
Second-seeded Alexander Zverev also went through to the last eight with a 6-4, 6-4 victory over Alexei Popyrin, but third-seeded Marin Cilic was beaten 7-5, 7-6 (2) by Marius Copil.
There were also wins for Stefanos Tsitsipas, Daniil Medvedev, Roberto Bautista Agut and Taylor Fritz.