Tim Paine conceded he was having a torrid time after missing two key opportunities to review umpiring decisions that would have been overturned and brought his side important breakthroughs.
England built on their first-innings lead and finished the third day's play firmly placed in a match-winning position.
Meanwhile, the Australia bowling attack was left to toil at The Oval seeing minimal success in return and were not helped by Paine's indecision to review a couple of close lbw appeals.
Joe Denly was caught on the crease when he was on 54 by a sharp Mitchell Marsh delivery that swung back in but Australia did not send the not-out verdict upstairs.
Later, the visitors' skipper missed another chance of claiming a wicket when Jos Buttler, batting on 19, was adjudged not out by the on-field umpire.
Replays then suggested the Nathan Lyon delivery would have gone on to strike the stumps.
"I'm getting it wrong," said a peevish Paine. "I don't know what else to say. We're having a mare (nightmare). We've got it wrong."
"It's fast. It's a tough job as I've said throughout the whole Test series. I've got a new respect for umpiring, particularly in Test cricket because it's a hard job."
He sarcastically admitted he might have to enroll in an "umpiring school" to correct his habit of missed reviews.
Australia's struggles with DRS were at the fore in their defeat at Headingley when they had earlier used up the reviews and could not challenge a not-out decision against Ben Stokes in the dying moments of the match.
In the aftermath of the one-wicket loss, Paine had suggested hiring someone else to oversee the team's reviews.
Paine said contrary to popular opinion, it was in fact hard to judge the trajectory of the ball behind the stumps.
He still believed Australia had a chance to register their first Ashes series win in England in 18 years.
"The only thing that's been a bit upsetting this Test match is our catching and our referrals but that's not anything new," he added.
He lauded Steve Smith's incredible effort in the slips to take a diving catch off an edge from Chris Woakes' bat.
"Cricketers like him, I think Stokes is the same, they're just in the contest and in the game all the time," he said.
"That's what makes great cricketers great because they're always in the contest, they're always aware of what's happening. It was a pretty special catch."