While his fellow Sydneysider Alexei Popyrin, Australia's No.2, enjoyed a victory to set up a tilt at Daniil Medvedev in the third round, Thompson's withdrawal because of an oblique muscle injury is a blow with the season's second grand slam, the French Open, just over a fortnight away.
Thompson had admitted after his first-round win over rising French star Giovanni Mpetshi Perricard that he was still harbouring the injury which forced him out of the Barcelona Open and made him give the Madrid Open a miss too amid a clay-court campaign that also featured a groin ailment during the Monte Carlo Masters.
"I was actually not sure if I was going to be able to play today, but I'm glad I gave it a go -- but my body might not be thanking me tomorrow," Thompson had said after the Mpetshi Perricard match on Wednesday, and his fears were justified as he had to pull out of his second-round date against world No.29 Brandon Nakashima.
Popyrin, though, after three straight defeats in his own faltering clay-court campaign, was happy to get back to winning ways, overcoming a tough second-set challenge to beat Spanish qualifier, world No.139 Carlos Taberner 6-1 7-6 (7-4).
That sets up the 24th seed Popyrin, who recently added South African former top-tenner Wayne Ferreira to his coaching team, with a real test of how his game is shaping up when he tackles Medvedev, the 10th seed who looked good in his 6-4 6-2 win over Briton Cameron Norrie.
All eyes at the Foro Italico were on the return of Carlos Alcaraz following his brief injury layoff and the Spanish superstar appeared sharp in a 6-3 6-3 win over Serbian qualifier Dusan Lajovic despite donning a brace stretching down from just below his knee to the top of his right leg.
Alcaraz had withdrawn from Madrid with a leg injury which had hampered him in the Barcelona final, but was surprised how well he played on his comeback, saying: "The body felt great. I just moved well and made a few good sprints without any pain. I think I passed the test today."
Rome is braced for the return after his doping ban of Italy's national sporting hero Jannik Sinner, who opens up against 99th-ranked Mariano Navone on Saturday, while Australia's main man Alex de Minaur launches his bid against another Italian, wildcard Luca Nardi.
