Magical Glenn Maxwell reflects on 'greatest' ODI innings after beating Afghanistan

For the Australian all-rounder, though, it was just "great fun".

Maxwell smashed an unbeaten 201 off 128 balls in Mumbai on Tuesday, single-handedly guiding Australia to an improbable three-wicket win that sealed their spot in the semi-finals.

"It was great fun. It just felt like it was me and Patty (Cummins) just having fun out there," he told reporters of the partnership with his captain, having come together at 91 for seven.

"We were keeping each other pretty calm with jokes most of the time.

"When he first came out, he goes, 'Don't worry, they’re four overs down, they're going to have an extra fielder in for the last four overs'.

"We just tried to keep the mood nice and light. Obviously, it wasn't an ideal situation, but we just tried to relax each other as much as we could."

Australia's first double-century maker in ODIs, Maxwell also became the first anywhere to reach 200 during an ODI chase.

He became the third player to score 200 at a World Cup, following Chris Gayle's 219 against Zimbabwe in 2015 and Martin Guptill's 237 not out against West Indies in 2015.

Cummins declared Maxwell's knock "the greatest ODI innings" and plenty agreed, including former England captain Michael Vaughan and Australia's past master-blaster Adam Gilchrist.

Former India all-rounder and cricket analyst Irfan Pathan went a step further, calling it the "best ever white ball inning" on social media.

Maxwell's night looked over when on 147 he slumped to the ground after taking a single. Cramped up in both legs, he also suffered a back spasm while lying down.

There was talk of retiring from his innings and possibly returning but medical staff warned that coming down the stairs to return to the crease might prove impossible.

So he elected to plough on and rely mostly on his reflexes and hands to smash anything in the zone.

"So that probably made the job a bit more simple," he said.

"It wasn't all just, like, chaotic swinging but there was a bit of planning to it."

The Melbourne man has produced plenty of incredible moments through a roller-coaster career but the World Cup has seen 'peak Maxwell'.

Coming back from an ankle injury, he played the second spinner role to perfection in the early matches then blasted the fastest World Cup century against the Netherlands when he raced to his hundred in 40 balls.

He then suffered a concussion after falling off the back of a golf cart, missing the game against England before slotting back in to face Afghanistan.

Australia play their last group stage match against Bangladesh in Pune on Saturday.

Before limping off for more recovery, Maxwell joked that all the drama had happened since his family had joined him in India.

"It's been a weird, weird couple of weeks ... To be in the semi-finals is a great feeling. Hopefully we enjoy a few days in Pune," he said.

"I'll stay away from the golf carts."