Millwall boss Gary Rowett is hopeful Troy Parrott's quad injury is just "a mild strain" that won't keep the Republic of Ireland attacker out for more than two to three weeks.
Parrott scored in the Lions' 3-0 friendly win over Southend United on Saturday - his second goal in two pre-season appearances since making the move to the Den from Spurs on loan - but he was forced to come off with about 15 minutes to go.
On Sunday, Ireland manager Stephen Kenny called Sean Maguire into his panel for the Nations League games with Bulgaria and Finland with Parrott returning to his club for treatment.
It's a blow for the Dubliner, who likely would have been given more minutes to shine in a green jersey.
However, Rowett is confident he won't be on the sidelines for long.
"He came off after 30 minutes of the second half and just felt his quad," he told The South London Press.
"And then when we examined him afterwards without a scan it looked as if he had just a mild strain of it.
"We don't think it is too much more serious than that. Any strain is usually two to three weeks out to make sure you don’t re-injure or come back too soon.
"He'd been doing really well but the rigours of pre-season is asking an awful lot of an 18-year-old. Hopefully it is not too serious."
Parrott joined Championship side Millwall on a season-long switch from Spurs at the start of August.
He made four first-team appearances for the Premier League side last season but Jose Mourinho had made it clear he needed to move out to get more first-team minutes, saying last March that Parrott is "not ready" for the top flight.
Rowett has been full of praise for how he's acclimatised to life at Millwall and expects Parrott to get back on the field sooner rather than later.
"Like any player he has got a massive opportunity to play for his country and I’m sure he wanted to do that," Rowett added.
"But as a precaution he can get treatment and see how he responds. We don’t think it is serious but it can still be two to three weeks out of action.
"It’s not ideal but nothing much to worry about."