Australia captain Tim Paine admitted he was having "a mare" after twice failing to review umpiring decisions in the fifth Ashes Test even though the challenges would have brought wickets.

England, seeking to level the series at 2-2, are firmly in control of the final Test with two days to go, 382 runs ahead with two second-innings wickets left.

Australia toiled in the field at the Oval on the third day of the match on Saturday and were not helped by Paine's misjudgements.

Joe Denly, who went on to score 94, should have been out lbw to Mitchell Marsh when he was on 54 but Australia opted not to review the not-out decision.

Later on the skipper, who is the team's wicketkeeper, failed to review a not-out decision against Jos Buttler after an appeal for lbw, with replays showing Nathan Lyon's delivery would have hit the stumps.

Buttler, then on 19, went on to score 47.

"I'm getting it wrong," said a tetchy Paine. "I don't know what else to say. We're having a mare (nightmare). We've got it wrong."

"It's fast," he added. "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."

When asked what he could do about it, he said sarcastically that he would enrol in "umpiring school" when he returned home to Australia.

Paine said after his side's defeat in the third Test at Headingley that he would be putting someone else in charge of the team's reviews.

During the closing stages of that match, Lyon had a huge appeal for lbw against Ben Stokes but the England vice-captain was given not out and Australia could not challenge that verdict as they had used up all their reviews.

Their misery was compounded when replays revealed that Stokes would have been given out.

Paine said it was sometimes difficult to judge from behind the stumps, saying he was not sure where the ball hit Denly, for example.

The skipper said his team, guaranteed to retain the Ashes urn, still had a chance to win the series outright.

"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 described his top-scorer Steve Smith as a "freak" after he took a stunning diving slip catch late on to see the back of Chris Woakes.

"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."