The 32-year-old striker, who has endured an injury-hit season, did not return to Napoli's training ground following his withdrawal from Belgium's international squad for friendlies against the United States and Mexico. Instead, Lukaku remained in Belgium to continue rehabilitation work on a recurring fitness issue.

Napoli confirmed his absence in a strongly worded statement, saying: "SSC Napoli can confirm that Romelu Lukaku did not respond to today's call to return to training. The club reserves the right to consider taking the appropriate disciplinary action, as well as to determine whether the player will continue to train with the team for an indefinite period."

The situation has escalated into a standoff between player and club, with Lukaku's decision to remain in Belgium for treatment reportedly not aligning with Napoli's expectations for his recovery process.

Lukaku's season has been heavily disrupted by a hamstring injury that ruled him out for the opening months of the campaign. Since returning, he has been restricted almost entirely to substitute appearances and has played just 64 minutes of football overall this season, scoring once in limited action.

His lack of continuity has also impacted his international availability. He withdrew from Belgium duty as a precaution, with the aim of regaining full fitness ahead of a potential fourth World Cup appearance later this year.

Despite his struggles, Lukaku has insisted he remains fully committed to Napoli and determined to return to top form.

In a detailed statement shared on social media, the former Chelsea, Everton and Manchester United forward explained that recent scans revealed inflammation and fluid around his hip flexor, close to previous scar tissue.

"The truth is the last few weeks I wasn't feeling right physically and I had it checked out while I was in Belgium," he said. "It showed there was inflammation and fluid in the iliopsoas muscle near the scar tissue."

He added that repeated setbacks had affected him both physically and mentally, but stressed his desire to return stronger.

"I could never turn my back on Napoli, never. There's nothing more I would love than to play and win with my team. But right now I have to make sure I'm 100 percent physically."

Lukaku, who joined Napoli in 2024 and scored 14 goals in the previous campaign as they secured the Serie A title, has found his second season far more difficult due to injury problems and limited rhythm.

Reports in Italy suggest Napoli were expecting him to return from Belgium after international withdrawal, but his decision not to report has triggered internal frustration and opened the door to potential disciplinary measures.

Napoli currently sit third in Serie A, seven points behind leaders Inter Milan, with key fixtures ahead that could shape their season.

For now, Lukaku's immediate future at the club appears uncertain, with both sides yet to publicly signal how the situation will be resolved.

Super-sub Ollie Watkins' 90th-minute winner fires England into second successive Euro final