Matty had a collision with Marlon Harewood that resulted in the striker landing on his knee.
Alan Pardew described the incident yesterday, “Matty is doubtful for the first three games for sure. It is a big blow.
“They had a coming together and Marlon landed on his knee - and if Marlon landed on your knee you wouldn't be feeling too clever!”
Pardew will now step up his attempts to bring in another wide player before the start of the season with James Milner of Newcastle and a loan move for Chelsea's Shaun Wright-Phillips both being touted as possible targets.