Former world No. 3 Stan Wawrinka, on the comeback trail after battling a foot injury for more than a year, defeated 14th-seeded Reilly Opelka 3-6, 7-5, 6-2 in the opening round of the Internazionali BNL d'Italia in Rome on Monday.

The victory gave the Swiss native his first ATP Tour victory sinceFebruary 2021. It was just the second match in the return to play for Wawrinka, who was delighted by the outcome.

"I was feeling good on the court. Physically I was feeling great," Wawrinka said. "When you don't win a match in more than a year, you start to think about it more than what you should and not focus on the right things.

"In general I think it was a great match, great battle. I stayed positive. I start to feel much better with my tennis by the end of the second set, and the third set. I'm really happy with this victory."

Wawrinka, 37, fought back from a set down and a 2-4 deficit in the second set, breaking the big-serving Opelka in the eighth game of the match to tie the score at 4-4. He fended off five break points three games later to go up 6-5, then broke Opelka's serve again to win the set.

Next up for Wawrinka will be Laslo Djere of Serbia, who beat Croatia's Borna Coric 6-2, 6-7 (3), 6-2.

The 13th seed, Denis Shapovalov of Canada, also needed three sets to defeat Italian Lorenzo Sonego -- and the home crowd.

As Shapovalov argued with the chair umpire in the second set and was assessed a code violation for stepping beyond the net, the crowd began to boo him. Frustrated, he turned to the crowd and yelled, "shut the (expletive) up."

He went on to lose the set but prevailed 7-6 (5), 3-6, 6-3 to win the three hour, 11-minute match. Shapovalov apologized to chair umpire Richard Haigh after the match.

"A lot of things happened in the heat of the moment. I need to be better with my behavior," said Shapovalov, who will face Georgia's Nikoloz Basilashvili in the second round on Tuesday. "It was my mistake. I'll know the rule for next time. I definitely won't step over the net."

Basilashvili defeated Daniel Evans of Great Britain 7-6 (2), 6-2.

Another Italian, Fabio Fognini, advanced to the second round after defeating Austrian Dominic Thiem on center court, 6-4, 7-6 (5). It was Fognini's first win in Rome since 2019.

Spain's Alejandro Davidovich Fokina topped Ilya Ivashka of Belarus 6-2, 4-6, 6-4 in two hours and 42 minutes. Davidovich Fokina moved to 8-3 on clay courts this year and next will face Canada's Felix Auger-Aliassime, the eighth seed.

In other action, Pablo Carreno Busta of Spain, the 15th seed, ousted Federico Delbonis of Argentina 6-3, 6-2; Jenson Brooksby beat Italian wild card Flavio Cobolli 6-3, 6-4; another American, Marcos Giron, came back to defeat Alexander Bublik of Kazakhstan 3-6, 6-4, 6-3; and Tommy Paul eliminated Albert Ramos-Vinolas of Spain 6-4, 6-4.

Also, Botic van de Zandschulp of the Netherlands beat Sebastian Korda 6-4, 6-1; Russian Karen Khachanov topped Italian Giulio Zeppieri 6-3, 6-4; and Alex De Minaur of Australia defeated Dusan Lajovic of Serbia 6-4, 6-1.