Reigning champion Casper Ruud made a winning start to his Geneva Open title defence after defeating Benoit Paire in straight sets on Wednesday.
The world number eight triumphed in Switzerland 12 months ago with victory over Denis Shapovalov in the final, claiming the first of five ATP titles he won during an impressive campaign.
Fresh from reaching the semi-finals in Rome, the Norwegian – also a winner in Buenos Aires and a Miami runner-up this season – made a dominant start.
Although he was broken in game three of the opening set, Ruud responded immediately and a further four breaks wrapped up a commanding 6-3 6-1 victory in just 55 minutes.
Meanwhile, Reilly Opelka registered his first win on European clay this season as he saw off Christopher O'Connell.
Despite triumphing in Dallas and Houston earlier this year, Opelka has suffered first-round exits in Munich, Madrid and Rome since the latter.
Nevertheless, the fourth seed was in fine form in Geneva, hitting 13 aces on the way to defeating the Australian qualifier.
However, there was no joy for 2021 runner-up Shapovalov as the third seed crashed out 6-4 6-7(2) 6-3 to Ilya Ivashka.
Fifth seed Nikoloz Basilashvili fell 6-4 6-3 at the hands of 2015 finalist Joao Sousa, who progresses beyond round two for the first time since reaching the Championship match seven years ago.
There were more surprise defeats in Lyon, where second seed Pablo Carreno Busta was beaten 7-5 6-3 by Federico Coria.
After taking a close opening set, the world number 59 rallied from 3-1 down in the second to reach his fourth quarter-final of the season on clay.
Karen Khachanov also bowed out to Marrakech runner-up Alex Molcan 6-2 7-6(4), while Munich champion Holger Rune built on his momentum with a 6-4 6-3 victory over Adrian Mannarino.