Travis Head’s third century of the series lifts Australia to 281-3 at lunch on Day 3

Travis Head posted his third century of the series to lift Australia to 281-3 at lunch on Day 3 of the fifth and final Ashes test, justifying his elevation to open the batting and underlining his intent to make it a permanent move.

Head raised his hundred from 105 balls on Tuesday, becoming the first Australian opener since Matthew Hayden in 2002-03 to post three centuries in an Ashes series.

He'd resumed on 91 with Australia at 166-2 overnight in reply to England's 384. Australia added 115 runs the morning session for the loss of nightwatchman Michael Neser, who scored 24 from 90 deliveries, cutting the first-innings deficit to 103 runs.

At the interval, Head was unbeaten on 162 from 160 deliveries, adding 41 runs after he was dropped in the outfield. Steve Smith was 16 not out.

The 32-year-old left-hander reached triple figures with the 17th boundary of his innings, following his 69-ball century in Perth in the first test - when he was promoted up the order from No. 5 in the second innings because Usman Khawaja was injured - and his 170 in Adelaide in the third test.

He swung his bat around in a circular motion to celebrate, then put his batting helmet on top of the bat handle and held it aloft to the Sydney Cricket Ground crowd.

The two previous centuries contributed heavily to Australia retaining the Ashes in 11 days of action. In Sydney, he's determined to help the home team rebound after England's drought-breaking win last week in the fourth test in Melbourne.

Head was beaten a few times early on Day 3 by deliveries from Stokes and Tongue before reaching triple figures, then crashed three consecutive boundaries in Matthew Potts' first over to take Australia's total past 200.

Head had a big reprieve when he was dropped on 121 by Will Jacks from Brydon Carse's bowling. Head hit a short ball out to mid-wicket where Jacks got two hands to it but put down a regulation chance. It was England's 12th dropped catch of the series.

He slowed his run-rate for a while but then accelerated after Neser was caught behind off Carse, ending a 72-run third-wicket stand.

Head hit the first six of the innings and then surpassed 150 with another boundary to take him to 153 from 152 balls. His tally was up to 24 boundaries and a six by lunch on Day 3.

Zak Crawley couldn't grab a tough, low chance at leg slip when Smith got an inside edge to Josh Tongue in the next-to-last over of the session.

And Jacks put down a second catch - a much tougher chance - a return catch from Head in the over before the interval that went quickly to his left and also had the umpire diving or cover.

England was already in DRS trouble after losing the third and last of its reviews on an lbw appeal from Carse when he hit Neser on the foot with a full delivery.

It was a dogged innings from Neser, who took four first-innings wickets and then went in as nightwatchman for 15 minutes before stumps on Day 2 and took a painful blow on the elbow.