St Mirren manager Alan Stubbs admits rough diamond Hayden Coulson needs further polishing if he wants to sparkle at the top level.


The 20-year-old England youth international has joined the Buddies on a one-year loan from Middlesbrough.


He gave another glimpse of his potential during Saturday's 6-0 romp over Dumbarton which sealed Saints' place in the Betfred Cup last 16, smashing the second-minute opener and coming close to a second after rattling the post.


But Paisley boss Stubbs believes his summer signing has room for improvement.


"He needs to make better decisions but in terms of potential he's got a lot," said the Englishman.


"If we want him to go to where we think he can, there's certainly aspects of his game he needs to tidy up."


Stubbs also handed Manchester United midfielder Matty Willock his debut against the Sons just 24 hours after securing the former St Johnstone loanee on another temporary deal.


He said: "Matty was very good. I said when we signed him that we needed someone with the attributes he's got.


"He gives a little bit more athleticism in there and an attacking threat going forward. We were happy to get 60 minutes into him today and we can build on that."