Kei Nishikori made a winning return after three weeks out injured, beating Dusan Lajovic 7-5 6-1 in the Swiss Indoors first round.
The third-seeded Japanese got the prime match slot after the opening ceremony at Roger Federer's hometown tournament which is missing the seven-time champion and Rafael Nadal, who ended their seasons through injury.
Nishikori, who retired with a glute muscle injury at the recent Japan Open, eased past the 77th-ranked Serbian Lajovic on Monday.
The 26-year-old Japanese star forced the first service break to lead 6-5 then reeled off three more breaks, and clinched the match when Lajovic's defensive lob struck the ceiling of the court.
Top-seeded Stan Wawrinka opens on Tuesday against fellow Swiss Marco Chiudinelli.
Two-time Basel champion Juan Martin del Potro of Argentina got a wild-card entry and plays on Wednesday.
