BASEL, Switzerland — Two-time Swiss Indoors champion Juan Martin del Porto beat Joao Sousa 6-1, 4-6, 6-1 to advance to the second round on Wednesday.
The fourth-seeded Del Potro dominated with his serve and sent down nine aces and 19 service winners against the 60th-ranked Portuguese.
Del Potro won back-to-back titles at Basel in 2012-13, both times beating hometown favorite Roger Federer in the final.
In a second round match Wednesday, fifth-seeded Jack Sock won 6-4, 2-6, 6-4 against Robin Haase of the Netherlands to be the only American victor as three others lost.
Sixth-seeded Spaniard Roberto Bautista Agut advanced to the quarterfinals beating Ryan Harrison 6-3, 7-6 (1). In first-round matches, Julien Benneteau of France beat Donald Young 6-4, 6-2 and Marton Fucsovics of Hungary won 6-0, 6-1 against Jared Donaldson.