Dublin will ignore a troublesome groin problem to lead Villa's attack in the absence of Stan Collymore against Leeds tonight.
Gregory admits that the performances of his pounds 5.75m signing from Coventry have been badly affected by the injury. He says that instant surgery would be the best option even though Dublin is willing to delay going under the surgeon's knife until the end of the campaign.
"Dion is not doing himself justice," Gregory said. "He's had rest and missed a couple of games but it hasn't cured the problem. It is still there.
"It's one of those injuries that he cannot do any more damage to than he has done already. He's having to play with the injury. It is a bit uncomfortable and you can see his lack of movement.
"He should play tomorrow. We will strap him up. He's desperate to get on the pitch and is willing to try and get through to the end of the season without having surgery.
"But he is not doing himself justice and if it becomes too unbearable and causes him too much embarrassment then we will have to make the decision for him to have surgery.
"If he does have to have surgery he could be out for several weeks but it might turn out to be the best option for him even though we are a little restricted in who we can select at present."
Paul Merson and Gareth Southgate will return for Gregory as they aim to bounce back from successive defeats at the hands of Newcastle and Blackburn.
Southgate has been troubled by a hip complaint which forced his withdrawal from the England squad to face France last week while Merson was ruled out of the same international with a back problem.
Gregory said: "I don't think there is too much wrong and in the last match against Blackburn we played well and created chances but paid for a couple of individual errors.
"We need a win now to give us a lift and a bit more self-belief. Two or three wins now and we are right back in the hunt.
"We are not too despondent even though a few pundits who said we weren't going to stay at the top have got a bit of a smug look on their faces after our last couple of results.
"This is the first hiccup I've had in my 12 months in charge and I'm disappointed to have slipped out of the top three but it is not as if we are mile adrift.
"We think we are going into the last part of the season still as serious title contenders."
Gregory admitted: "It is probably a good thing for us that we are going to be up against one of the in-form sides because that will bring the best out of us".
"In all honesty I couldn't give a monkey's what it looks like tomorrow night providing we get the three points to get back into the promotion race."
Gregory revealed that Collymore will not return to Villa from his stress counselling for another 10 days and that makes it even more urgent for Dublin to be patched up.Reuse content