David Warner erased any lingering doubt about his batting since his comeback to the Australian team from a 12-month ban with an almost run-a-ball century to help the defending World Cup champions hold off Pakistan by 41 runs on Wednesday.
Warner wasn't exactly back to his best, but he still reached his first hundred for Australia since 2017 from 102 balls, stroking 11 boundaries and a six in the process.
He launched the innings with a 146-run opening stand with skipper Aaron Finch (82) that set the foundation for a big total at Somerset's County Ground, although Australia's last six wickets fell for 30 as Pakistan rallied to restrict the total to 307.
Left-arm paceman Mohammad Amir led the Pakistan attack and completed a career-best haul of 5-30 when Mitchell Starc was caught at long-on to end Australia's innings in the 49th over.
Pakistan lost its first wicket in the third over to Pat Cummins (3-33) but kept the run chase tense with a series of batting contributions until skipper Sarfaraz Ahmed (40) was run out to end the innings at 266.
Imam-ul-Haq shared partnerships of 54 with Babar Azam (30) and 80 with Mohammad Hafeez (48) before he was caught behind off Cummins in the 26th over for 53.
Pakistan had a slide of 3-11 and its hopes appeared to fade at 147-5 when Hafeez was caught on the deep midwicket boundary to a rank full-toss from part-timer Finch, bowling slow left-arm orthodox, and Shoaib Malik was caught behind from an inside edge off Cummins in the next over.
But a 15-ball 32 from Hasan Ali and the 64-run eighth-wicket partnership between Sarfaraz and Wahab Riaz kept Pakistan right in the chase.
Wahab's 45 from 39 balls ended in a caught-behind decision only given after Australia reviewed the initial not out call because wicketkeeper Alex Carey was convinced Starc (2-43) had got a thin edge.
The keeper proved correct, and Starc picked up another wicket two balls later to make it 265-9. Sarfraz was the last man out, run out by Glenn Maxwell in the 46th over.
Until then, it was all about Warner.
When he edged between wicketkeeper and slip for a boundary in the 36th over to reach triple figures, he ran up the pitch before punching the air to celebrate his 15th ODI century — and his first in any format for Australia since a test against England in December 2017.
He was rubbed out of the representative game for 12 months for his part in a ball-tampering scandal in South Africa in March last year that rocked Australian cricket.
Warner was booed by the crowd in each of his previous appearances at the World Cup, and was under scrutiny from critics despite scoring runs because his unbeaten 89 against Afghanistan, his three against West Indies and his 56 against India all came at an uncharacteristically slow strike rate.
Warner was only jeered by the heavily pro-Pakistan crowd on Wednesday when he was dropped cold by Asif Ali at third man on 104, but that was more likely frustration at yet another fielding error from the Pakistani team.
His innings came to end with Australia at 242-4 in the 38th over, when he miscued Shaheen Afridi (2-70) to Imam at deep point.
Apart from Warner and Finch, nobody in the Australian lineup scored more than Shaun Marsh's 23 as Amir continued to trouble the batsmen with his movement off the seam.
The strike-rate seemed to be the only question over Warner's form and mental state in England, and he responded the best way he could.
Sarfaraz had no hesitation in sending Australia in to bat on Wednesday after back-to-back washouts on Days 12 and 13 and with rain on the forecast.
In the end, there were no interruptions for rain and Australia extended its ODI winning streak against Pakistan to nine, and improved to 3-1 from four games at the World Cup.