PNE new boy goes under the knife
The midfielder joined PNE from Manchester United for an undisclosed fee on Monday but knee surgery will delay his debut.
Grimshaw, 20, underwent the operation on Thursday morning to correct an injury which he has been carrying since being on loan at Motherwell in the first half of the season.
The injury was picked-up on the medical prior to him signing but after seeking advice from a specialist, North End were happy to get the deal done and quickly get him under the surgeon's knife.
At his Thursday morning press conference at Springfields, Grayson said: "That is why the medical went on a little bit, we have to do our due diligence on all players we sign.
"We saw there was a little bit of a problem with his knee, it wasn't a major problem, just something which needed clearing up.
"We were more than happy to sign the deal off and get it done.
"Then he can get the knee problem out of the way and be back in a few weeks time.
"We are glad to have him, Liam is another young, hungry player, enthusiastic and versatile who can add to the squad.
"He had the operation on Thursday morning.
"It is not a gamble at all, we spoke to the specialist and it is quite a common thing.
"Liam has been playing with the injury anyway but we felt for the long-term it was right to get it done now and out of the way.
"Once he is back fit, we want to get him involved in the squad as soon as possible.