He returned to fitness for the midweek clash with the Premier League club, but struggled to make his mark and had to be withdrawn at half-time.

"Troy got a kick on the ankle early on and he is a young lad, desperate to play and he has been devastated to be injured because he wants to play games," Rowett said.

"You could see he was struggling movement-wise. He probably should have come off (earlier) or I probably should have taken him off. It doesn't look great, but we'll see.

"Obviously it's a big blow for us because we haven't scored as many goals as we'd like anyway and Troy was brought in to give us that extra quality but at the moment he hasn't really been available."

Parrott was looking to help Millwall beat Burnley for the first time since February 2012, when a goal from then-loanee Harry Kane inspired the south Londoners to a 3-1 win.

After being prolific in Tottenham's academy, the once-capped Republic of Ireland international has played twice in the top flight but was sent out on loan this term to gain more experience.

Lining up in the number 10 role behind Matt Smith, Parrott was unable to get on the ball as Burnley won the third-round tie thanks to goals from Josh Brownhill and Matej Vydra.

Rowett added: "He's such an honest kid, who is desperate to score goals and do well for us.

"And he's fitted in brilliantly with the group and worked incredibly hard, so it is more frustration from his point of view.

"Even when he's struggling he wants to stay out there, so everything he is doing is for the right reasons, but he has probably got to learn if he makes the injury worse, he will be out for longer.

"He is a bright lad and it is disappointing so far we've not really had him available, but hopefully it is not too serious and he will be available soon."

Fellow Republic of Ireland prospect Jimmy Dunne ensured Parrott and Smith were kept quiet as he starred alongside Burnley debutant Bobby Thomas.

Goalkeeper Bailey Peacock-Farrell was also involved for the Clarets in a competitive game for the first time since he joined from Leeds last summer and impressed boss Sean Dyche.

"We like Bailey a lot and he is developing physically. We thought he came in and was too skinny, so he has put on a good bit of bulk," Dyche said.

"The only reason he didn't play in the last round (against Sheffield United) was because after lockdown, Nick Pope didn't play a lot of football.

"He went away with England and we thought he may have a chance, but didn't play so that's why Bailey didn't play the last round – we wanted to give Popey a competitive 90. We planned on Bailey playing at Millwall and he has done well."

Burnley will host Manchester City or Bournemouth next week and Dyche was also quizzed about a potential takeover at Turf Moor.

The 49-year-old insisted: "It is not about welcoming it or not welcoming it. It is not my business, it is the chairman, the board and the shareholders – amongst them they will make a decision if there is any news.

"I don't know anything about it, but if there is something in it, they will make the decisions and not me."