ACAPULCO, Mexico — Stanislas Wawrinka continued his recent uptick in form with a 6-4, 7-6(6) win over Ryan Harrison Monday to advance to the second round of the Acapulco International.

The Swiss started the first set with a break to set the tone but had to battle to hold off Harrison in the second set where the American earned a break to even it at 4-4.

Wawrinka clinched the match with his 26th winner of the night.

A three-time Grand Slam champion, Wawrinka reached the final of the Rotterdam Open last week. He lost to Frenchman Gael Monfils but it was his first appearance in a championship match since the 2017 French Open.

Wawrinka’s recent run has returned him to the top 50 in the ATP singles rankings at 42nd.

He will next face seventh seed Steve Johnson, who beat Mexican wild card Gerardo Lopez Villasenor 7-5, 7-5.

Eighth-seeded Australian John Millman defeated Spain’s Marcel Granollers 6-3, 6-4.

World No. 2 Rafa Nadal will open his bid for the title Tuesday against Mischa Zverev. Second seed Alexander Zverev and third seed John Isner will also begin their campaigns Tuesday. — Reuters