Dominic Thiem stayed on track for a place at the ATP World Tour Finals with a straight-sets win over Gerald Melzer at the Vienna Open, while David Goffin was a victor in Basel.
It took Thiem just 21 minutes to move one set up, and he broke to love in game eight of the second before serving out a 6-0 6-3 victory.
The Austrian third seed will take on Viktor Troicki, who beat Kevin Anderson 4-6 7-6 (7-5) 7-5, for a place in the quarter-finals as he aims to boost his hopes of featuring at the O2 Arena in London next month with a strong run.
Lucas Pouille and Roberto Bautista Agut were not as fortunate, though, the pair sustaining severe dents to their chances of making the Finals with first-round defeats.
Feliciano Lopez saved match point en route to a 6-4 2-6 7-5 triumph against Pouille, while Bautista Agut was defeated 6-3 7-5 by Jurgen Melzer.
Jo-Wilfried Tsonga remains in the hunt after a routine straight-sets win over Benjamin Becker and Gilles Simon set up a second-round match against Andy Murray by overcoming Guillermo Garcia-Lopez.
Goffin remains a chance of making the Finals and won his first-round clash at the Swiss Indoors, beating Marcos Baghdatis 6-4 7-6 (7-4).
Also in Basel, second seed Milos Raonic and sixth seed Grigor Dimitrov suffered shock defeats in the first round.
Raonic, who has already secured his place at the Finals, let a lead slip in a 3-6 6-3 6-3 defeat to Ricardas Berankis and Dimitrov fell 6-7 (9-11) 6-4 6-4 to Gilles Muller.
Top seed Stan Wawrinka suffered a scare when he lost the opening set against Marco Chiudinelli, but he fought back in fine fashion to complete a 6-7 (1-7) 6-1 6-4 victory.