Dan Turner opened the scoring for Leamington on 39 minutes with the home side looking comfortable.
But hopes of a victory were cruelly dashed when Brad Wright levelled from the spot on the stroke of full-time after a foul by Dan Meredith.
And Villa stole the win two minutes later following a fine finish from Kaden Young.
But Holleran felt it had been a great workout for the Brakes in tough conditions.
“It was a really tough game with the heat,” he said. “I thought the quality of the game was really good.
“It is very similar to Coventry and Walsall, they play through the pitch and make you work really hard.
“We dealt with most of that and looked a threat, there were some really good performances.
“I think the heat at the end left us tired and we ran out of legs. We made a lot of changes and we were out of shape for the last 10/15 minutes and never got hold of the ball.
“It was a really good workout and lots of pluses.
“It is all about August 6 and getting minutes into players. It is pre-season and we have to build things up gradually.
“It's a case of bedding everyone in and gradually getting up to speed.”
Kieran Cook fired wide before Tommi O’Reilly was off target for the Villa youngsters.
Jack Edwards headed over the bar, before Turner opened the scoring after Edwards played him in.
Villa were denied an almost certain leveller right on half time as the Leamington keeper produced a stunning save from Caleb Chukwuemeka.
Brakes gave very little away in the second half, looking solid defensively.
But they switched off as the final whistle approached with Villa claiming an unlikely win.
Leamington had no midweek game this week and travel to Halesowen on Saturday for their latest friendly.