ROME — The good news for Stan Wawrinka is that he finally feels physically fit again following surgery on his left knee.
The challenge now for the three-time Grand Slam champion is regaining his confidence and fluidity of movement on the court.
Playing his first match in three months, Wawrinka was more pleased than upset despite losing to 55th-ranked Steve Johnson 6-4, 6-4 Sunday in the first round of the Italian Open.
"My level is really high, better than what I expected," Wawrinka said, adding that he returned to proper on-court training only 12 days ago. "I'm happy with physically where I am right now."
Wawrinka committed 30 unforced errors to his American opponent's 17, was broken once in each set and failed to take advantage of his only two break opportunities.
"I was nervous during the match. A lot of hesitation with my game, with my movement and everything. Quite tight with my body. And that's going to make a big difference, especially for me, the way I move and the way I play," said Wawrinka, who draws enormous power from his robust frame.
"Even with that, it was a tough match. One, two points could have changed the match."
Wawrinka was operated on in August — twice — and returned in January at the Australian Open, where he was eliminated in the second round by Tennys Sandgren.
"When I came back in Australia, it was quite clear that I wasn't ready at all," the Swiss player said. "I wasn't at my top physically."
Wawrinka then retired from a match against 193rd-ranked Ilya Ivashka in Marseille, France, in February, citing a left knee injury — and hadn't played since.
"I wanted just to play a few tournaments to test the knee," he added. "I was positive to see that the knee was doing OK. But I knew I needed a lot of time to work on my fitness.
"And that's what I did when I stopped after Marseille. I went back to doing fitness almost every day for like three months. ... It was some tough weeks."
Magnus Norman has returned as Wawrinka's coach after leaving the Swiss player's staff in October — to Wawrinka's dismay at the time.
"He's going to keep working with me, hopefully the full year," Wawrinka said. "I still have a lot of work to do. I still need a lot of time, play matches, keep trying to play week after week to find the confidence back."
Three other Americans were also in action on the Foro Italico's red clay.
Twelfth-seeded Sam Querrey was eliminated by Peter Gojowczyk of Germany 6-2, 7-6 (7); 13th-seeded Jack Sock beat Spanish veteran David Ferrer 6-3, 6-4; and Ryan Harrison eliminated Yuichi Sugita of Japan 7-6 (5), 6-3.
Also, Italian wild card Lorenzo Sonego had strong fan support as he came back from a set down to defeat Adrian Mannarino 2-6, 7-6 (4), 6-3.
Meanwhile, two-time Wimbledon champion Petra Kvitova withdrew from the tournament citing a muscular injury that occurred during a grueling three-set win over Kiki Bertens in Saturday's Madrid Open final — her second title in two weeks after also taking the Prague Open.
"After these incredible two weeks of tennis my body needs to rest and recuperate," Kvitova said.
The women's tournament at the Foro Italico starts Monday.
It's the last Masters 100 event before the May 27-June 10 French Open — a tournament that Wawrinka won in 2015.