Marin Cilic advanced to the Swiss Indoors quarterfinals by beating Pablo Carreno Busta 6-0, 7-6 (4) on Thursday.
The fourth-seeded Cilic lost only five points in the first set against the 32nd-ranked Spaniard. The second set went with serve, and Cilic trailed in the tiebreaker before reeling off seven straight points.
Cilic will next play Marcel Granollers of Spain, who beat eighth-seeded Jack Sock of the United States 6-3, 6-1.
Earlier, Gilles Muller of Luxembourg earned a spot in the quarterfinals against Federico Delbonis of Argentina. Muller beat Florian Mayer of Germany 6-3, 6-2.