NEW DELHI: Jacob Bethell scored his maiden Test century on Wednesday, delivering at a crucial moment to keep England's hopes alive in the fifth and final Ashes Test at the Sydney Cricket Ground.

The 22-year-old Barbados-born allrounder walked to the crease in the first over of England's second innings after Mitchell Starc trapped Zac Crawley lbw on the fifth ball.

Bethell then anchored the innings, sharing vital partnerships of 81 with Ben Duckett (42), 32 with Joe Root (6), 102 with Harry Brook (42), and 45 with Jamie Smith (26), helping England reach 302/8 at stumps on Day 4 - a lead of 119 runs.

Jacob Bethell overtakes Ben Stokes, Joe Root with stunning maiden Test century

Bethell remained unbeaten on 142 off 232 balls, erasing England's first-innings deficit of 183 and keeping the contest alive on Day 5. While Australia had already secured the Ashes with victories in the first three Tests, England are determined to finish the series strongly, and Bethell's innings was a masterclass of composure under pressure.

"It was special to get the milestone," Bethell said in a TV interview. "To have the family over ... (and) to top it off with a hundred here is very special."

In just his sixth Test and only the second of this series, Bethell weathered a collapsing English batting lineup as wickets fell around him, with allrounder Beau Webster (3-51) emerging as an unlikely hero for Australia with his occasional offspin.

Webster turned the tide in Australia's favour with two wickets in three deliveries during the 52nd over. He first trapped Harry Brook lbw with a delivery that sharply turned off the rough and then dismissed Will Jacks, who swung recklessly and was caught in the deep by a tumbling Cameron Green for a second-ball duck. England suddenly slipped from 219/3 to 219/5, putting the pressure firmly back on Bethell and his teammates.

A crazy run out, first ball after the drinks break in the evening session, saw Jamie Smith (26) sent back by Bethell and well out of his ground when Jake Weatherald threw to Marnus Labuschagne to whip off the bails at the bowler's end.

Bethell were 123 at the time, and England at 264-6, when his injured skipper Ben Stokes went to the crease. The visitors added just three runs before Webster struck again, bowling around the wicket and enticing Stokes (1) to cut a turning ball and Steve Smith taking a sharp chance at slip.

Scott Boland returned to have Carse caught at slip, giving him two wickets for the innings after the big lbw decision against Root. Webster's wickets may have a positive spinoff for England on a turning pitch.

The Australians didn't take a specialist spinner into the match, instead relying on part-timers Travis Head and Webster, who also bowls medium pace.

England has Bethel and Jacks to bowl spin, and possibly Root.

Stokes injured

England picked up Australia's last three first-innings wickets for 49 runs after the hosts resumed at 518-7 but the morning session was overshadowed by an injury to Stokes. He bowled 10 deliveries before leaving the field for treatment on a right adductor problem. He didn't move freely when he batted.

Australia's innings

Australia's commanding innings was built on centuries from stand-in opener Head, his third of the series, and Steve Smith (138) and a late contribution from allrounder Webster, who remained unbeaten on 71.

The Australians will be pushing for victory to complete a 4-1 series win after retaining the Ashes in 11 days of action with wins in the first three tests. England is determined to narrow the margin after its drought-breaking win in the fourth test at Melbourne.

Smith was 129 overnight but didn't settle into a rhythm before he was caught behind off Josh Tongue's bowling, ending a 107-run eighth-wicket partnership with Webster.

The last two wickets fell within six deliveries, with Starc (5) bowled by a full delivery from Tongue that moved late off the seam and off-spinner Will Jacks (1-34) having Scott Boland caught for a first-ball duck at first slip.

The century was Smith's 13th in Ashes Tests, the 37th of his career and his fifth at the Sydney Cricket Ground. With it, he moved up to sixth on the all-time list of most test centuries.

(With AP Inputs)