Former Grand Slam champions Dominic Thiem and Stan Wawrinka focused on the positives on Tuesday after suffering straight-sets defeats on their return to competitive games following long spells of inactivity owing to injuries.

Former U.S. Open champion Thiem and three-time major winner Wawrinka were rusty as they made their Tour comebacks at the ATP Challenger Tour event in Marbella, Spain.

Playing his first match in nine months since suffering a wrist injury at the 2021 Mallorca Open, the 28-year-old Thiem lost 6-3, 6-4 to 228th-ranked Argentine Pedro Cachin.

Thiem, who twice finished runner-up at the French Open and once at the Australian Open before winning the 2020 U.S. Open title, said it was a day with "big emotions and mixed feelings".

"You can imagine how happy I was today to be on a tennis court, doing what I love the most: playing tennis and competing again," he said in an Instagram post, adding that the defeat was the "bitter part".

"After all these months, all those setbacks I had in the past few months, I was able to play again to feel the adrenaline of the competition. I felt like a player again."

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Wawrinka, who turned 37 recently, suffered a foot injury at the start of 2021 and underwent surgery. He lost 6-2, 6-4 to Sweden's 131st-ranked Elias Ymer in his first outing since his opening loss at the Qatar Open in early March last year.

"I think physically it was good, it was really positive," the Swiss told reporters. "I was super happy to be back playing a tournament, to get the emotion, to get the stress of a match again.

"I've been practising well and I'm going to keep practising and keep building for the next few weeks. I'm not worried at all."