Seeded Spanish players Albert Montanes and Marcel Granollers won in straight sets to reach the second round of the Bet-at-Home Cup in Kitzbuehel, Austria, on Monday.
The only seeded players in action on the opening day, No. 7 Montanes served eight aces in defeating Adrian Ungur of Romania 6-4, 6-2, while No. 8 Granollers beat Mate Pavic of Croatia 7-6 (7/2), 6-2.
Granollers saved all six break points.
He next faces Horacio Zeballos of Argentina, who beat Martin Fischer of Austria 7-5, 1-6, 6-3.
Leonardo Mayer of Argentina defeated Kenny de Schepper of France 6-4, 6-4 to set up a second-round match against top seed Philipp Kohlschreiber of Germany.
Dominic Thiem rallied from 4-1 down in the second set to beat Andrey Kuznetsov of Russia 6-2, 7-5.
It was the first ATP Tour match this season for the world No. 268 Thiem because of a viral illness. He next faces fourth seed Jurgen Melzer in an all-Austrian clash.
Daniel Gimeno-Traver of Spain conceded only nine points on serve in routing Antonio Veic of Croatia 6-1, 6-3.
The top four seeds have a bye in the opening round.