Wawrinka, formerly ranked No. 3 in the world, will face top-seeded Daniil Medvedev of Russia in the second round in Metz. Another former World No. 3, Austria's Dominic Thiem, beat Frenchman Richard Gasquet 6-3, 7-6 (3).
Seventh-seeded Alexander Bublik of Kazakhstan advanced in three sets over Evan Furness of France, while a pair of top 10 seeds were upset. Sweden's Mikael Ymer defeated eighth-seeded Frenchman Adrian Mannarino 7-5, 6-0, and in the lone second-round match, Sebastian Korda recorded a 6-3, 7-6 (6) victory over third-seeded Lorenzo Musetti of Italy.
San Diego Open
Third-seeded Marcos Giron of the United States and seventh-seeded James Duckworth of Australia became the first two players to advance to the quarterfinals in San Diego.
Giron downed Argentina's Tomas Martin Etcheverry 6-4, 6-3, and Duckworth eliminated US qualifier Mitchell Krueger 6-3, 7-6 (4).
The final four first-round matches were also played on Wednesday. Sixth-seeded Alejandro Tabilo of Chile beat the United States' Steve Johnson 7-5, 6-2. Colombia's Daniel Elahi Galan topped Switzerland's Marc-Andrea Huesler 6-3, 7-5, and the United States' Mackenzie McDonald routed Switzerland's Henri Laaksonen 6-0, 6-2.
Christopher O'Connell won an all-Australian matchup when Jason Kubler resigned before the third set. Kubler took the first set 6-4 and lost the second set 6-3.