Tim Paine joked he will enrol on an umpiring course after conceding Australia are having "a mare" with their reviews during the Ashes.

Australia finished day three of the fifth and final Test trailing England by 382 runs. The tourists need to avoid defeat to win the series outright having already retained the urn but endured a challenging day in the field as England closed on 318-8.

Joe Denly was the star for England with 94, though Australia could have dismissed him for considerably fewer runs had they reviewed after Mitchell Marsh struck the opener on the pads.

Denly was given not out on the field but Hawk-Eye showed the ball would have gone on to hit the stumps, as it would later in the innings when Australia again chose not to review after Nathan Lyon hit Jos Buttler, who made a fluent 46, in front.

Asked in a media conference what he can do to improve his judgment, the Australia skipper responded sarcastically: "I'm going to do some umpire school when I get home, I'll enrol in a level three umpiring course and see if I can get them right.

"I'm getting it wrong, I don't know what else to say, we're having a mare. We've got it wrong, we're not deliberately getting together and saying, 'Gee I reckon that's out Gaz, you want to refer it? Nah let's let him keep batting.'

"We're getting it wrong, it happens, 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 bloody hard job.

"For years players have whinged about umpiring and now we've got it in our hands a little bit and we're finding that it's hard."

Australia appeared tired and frustrated as their long and chastening day in the field dragged on, though Paine had no issues with his side's application on Saturday.

"The last hour of today, our energy is still really good in the field, our bowlers have run in every single day we've asked them to, they've done a fantastic job," added Paine.

"The only thing that's been a little bit disappointing in this Test match is our catching and our referrals."