Greg's yellow card collection is costly
The left-back was booked for a challenge on Anthony Knockaert – his 10th caution of the season, which triggers a two-match ban.
However, if Ipswich’s visit is postponed because of their involvement in the FA Cup that weekend – they have a replay on Tuesday – the ban will carry over to the Cardiff game on January 31.
North End boss Grayson said: “Greg’s booking looked a bit harsh to be fair.
“Speaking to the referee afterwards, he said it was an accumulation of tackles which led to it.
“Tommy Spurr has been waiting in the wings and he will come into the team.”
Cunningham will join midfielder Ben Pearson on football’s naughty step against Villa.
Pearson got to the 10 yellows mark a game earlier and missed the Brighton win.
When players have missed games this term, the depth of the squad put together at Preston has generally come into its own.
Grayson said: “Look at the players we had out against Brighton.
“Pearson and Beckford were suspended, DJ was ill and Alex Baptiste injured.
“You have to deal with things like that and players have been coming in and doing a good job for us.
“When you look at the 14 who finished the game, the average age was young, after Liam Grimshaw and Tom Barkhuizen came on.
“We have a hungry bunch of players, some of who were not on the bench. I decided on Stevie May over Eoin Doyle.”