Grealish strikes late to push Bluebirds out of automatic promotion places
Paterson who was declared fit to start having been withdrawn during the second half of the defeat to Wolves, although Joe Ralls was once again unavailable for the Bluebirds.
There was also a late change for the hosts as Republic of Ireland international Glenn Whelan started in place of the injured Birkir Bjarnason.
But while the Cardiff faithful were winning the early vocal battle in the stands, it was the home side who started the brighter on the pitch.
And they almost silenced the travelling supporters from South Wales as Lewis Grabban - the man heavily linked with a move to the Welsh capital during the January transfer window - fired into the side netting from close range.
But that early wake-up call seemed to do the trick for the visitors who grew in confidence, doing their best to force the hosts back and pressing at every opportunity.
It was that high intensity approach that almost saw the Bluebirds go infront in the 16th minute as MendezLaing won possession in the centre of the park, with the winger playing a neat one-two with Kenneth Zohore before drilling across Sam Johnstone’s goal, only to see his effort cannon back off the post.
Clearly buoyed by the opportunity, the Bluebirds continued to enjoy success on the counter attack.
And Mendez-Laing - having been dropped to the bench for the home clash with Wolves - was proving to be a real thorn in Villa’s left-hand side, so much so that Conor Hourihane resorted to hacking down the wideman midway through the opening half, a challenge that earned the Irishman a yellow card from referee Jeremy Simpson.
The hosts were dealt a blow soon after as left-back Axel Tuanzebe - on loan from Manchester United - was forced off through injury, being replaced by James Bree who was a late addition to Villa’s bench following the withdrawal of Bjarnason.