David Goffin moved into the second round of the Abierto Mexicano in Acapulco, while John Isner was the first seed to exit the tournament.
Five of the world's top 11 are in action in Mexico and with Novak Djokovic and Rafael Nadal beginning their campaigns on Tuesday night, it was Goffin who headlined the opening day of the first round.
The Belgian, seeded fifth and ranked just outside the world's top 10, has already lost in two finals this year but he had little trouble against France's Stephane Robert.
Goffin lost just three games as he raced through in just 54 minutes to set up a second round meeting with either Britain's Kyle Edmund or American Sam Querrey who meet on Tuesday.
Djokovic accepted a wild card and faces an awkward first round opponent in the shape of Martin Klizan, while Nadal faces an even tougher test in Mischa Zverev - the man who ended Andy Murray's Australian Open in the fourth round.
Elsewhere in the first round, Isner lost the battle of the Americans as he went down in straight sets to world No 26 Steve Johnson.
Johnson, a quarter-finalist in Delray Beach last week, came through 6-4 6-4 and will face another American in round two after Ernesto Esobedo justified his wild card with a victory over Stefan Kozlov.
Adrian Mannarino, Borna Coric and Jordan Thompson also booked their place in the last 16, Mannarino and Thompson both coming from a set down to secure three set victories.
With most of the big names in action at 500 events in Mexico and Dubai, the week's third tournament is on the clay of Sao Paolo at the Brasil Open.
Renzo Olivo, Gastao Elias and Guido Pella all went through to the second round with straight sets victories.
