In demand Dorrans awarded new West Brom contract
The Baggies have rejected three bids from West Ham for the 23 year old Scotland international and have now handed Dorrans a four-year deal, with the option of a further 12 months in the club's favour.
"I'm delighted Graham has signed a new long-term contract, which is fully deserved," Di Matteo told the club's official website.
"He made excellent progress last season and we're now very hopeful he can make the step up to the Premier League.
"There has been a lot of media speculation about Graham's future, but it hasn't affected him one bit.
"Ever since he has reported back for pre-season training, his attitude has been as spot on as it always is and I know for a fact how much he's looking forward to the new season.
"The exciting thing is that Graham knows he still has a lot of work to do and is yet to reach his full potential."