Australian qualifier Alexei Popyrin has advanced to the second round of the Italian Open by beating his compatriot, Chris O'Connell, in straight sets.

Popyrin, ranked No.77, won 6-2 7-6 (7-5) at the Foro Italico on Wednesday evening and will now face No.10 seed Felix Auger-Aliassime.

Two breaks of serve were enough to give Popyrin, the 23-year-old Sydneysider, the opening set.

The second was much closer but Popyrin - who served 10 aces to none from O'Connell - took it on a tense tiebreaker.

Australian qualifier Thanasi Kokkinakis is also through. He was leading Jaume Munar 4-2 in the first set when his Spanish opponent retired due to lower back pain.

Kokkinakis will next face local favourite Jannik Sinner.

Veteran Stan Wawrinka wasted little time securing a 6-2 6-4 win over Ilya Ivashka in the first round after the start was delayed for 90 minutes due to rain.

At 38, Wawrinka is the oldest man in the tournament but he dominated Ivashka, hitting more than twice as many winners as his opponent.

Wawrinka, a three-time Grand Slam champion, next faces 26th-seeded Grigor Dimitrov, with the winner potentially meeting top-ranked Novak Djokovic in the third round.

"My dream is to win another trophy, another tournament," Wawrinka said. "Of course, I'm getting older, it's getting more and more difficult. The passion and the love for the sport is still there; that's why I keep pushing myself."

Djokovic, who has a first-round bye, will open against Argentina's Tomas Martin Etcheverry.

Also advancing on the red clay of the Foro Italico were Alexander Bublik, Cristian Garin, Marton Fucsovics and Sebastian Baez.

In a clash of the 35-year-olds, Andy Murray was beaten by fellow veteran Fabio Fognini.

Murray, fresh from claiming success at an ATP Challenger event in Aix-en-Provence on Sunday, had hoped to extend his five-match winning streak but instead was edged out 6-4 4-6 6-4.

In women's action, Lesia Tsurenko eliminated two-time champion Elina Svitolina in all-Ukrainian matchup.

Sloane Stephens beat Nadia Podoroska 6-4 6-1 and next meets No.14 seed Victoria Azarenka.