The 24-year-old Brazilian – hat-trick hero in the win at Chelsea on February 4 – went off after just 19 minutes following an awkward fall at Molineux, and has since undergone scans.

The midlands club have not put a timescale on Cunha's recovery but O'Neil has acknowledged his absence comes as a "big blow".

"It's a fairly significant injury to his hamstring," O'Neil told the club's website. "There's no timeline on it. I've spoken to Matheus a lot and he just wants to keep pushing to get back as soon as he can.

"He's started working on it already, so we're just going to monitor it week by week, day by day, see how far he can come and how quickly we can get him back. He's keen to get back out there as soon as possible.

"It's obviously a big blow to us, to the team and Matheus because of the work he's been doing – the form he was in was exceptional. These things happen, every team suffers injuries.

"Channy (Hwang Hee-chan) was gone for over a month with the Asian Cup and we managed to keep ploughing on and we need to do the same without Matheus."