Topley rolled his left ankle after standing on a boundary advertisement cushion then landing awkwardly during some catching drills ahead of England’s warm-up win over Pakistan in Brisbane on Monday.
Scans have shown ligament damage so Mills, one of England’s three travelling reserves, has been upgraded to the 15-strong squad, with the change ratified by the International Cricket Council.
“Sussex seamer Tymal Mills has been drafted into England’s squad, having travelled to Australia as a reserve.”
Lancashire fast bowler Richard Gleeson is also on standby in Australia but England have gone for more of a like-for-like replacement in Mills, who has not played since August 10 because of a toe injury.
Luke Wood, another left-arm fast bowler, will link up with England in Melbourne, where they will be heading after opening their campaign in Perth on Saturday against Afghanistan.
It has not been determined when Topley will go back home and while he is not expected to have an operation he will be assessed on his return to the UK and is likely to be out until early next year.
The ICC rubberstamping Mills is an unfortunate role reversal from last year’s World Cup, when he was an injury withdrawal midway through the tournament because of a thigh strain with the 6ft 7in Topley coming into England’s squad.
While Topley did not make any appearances then, he has gone on to become an increasingly dependable figure in 2022, having overcome multiple stress fractures in his back in recent years that threatened to derail his career.
Topley has taken 17 wickets in 16 T20s this year – the most by any England bowler – with an economy rate of 7.8 impressive given he operates mainly in the powerplay at the death.
The 28-year-old – who is currently ranked as the second-best seamer in T20 internationals, in a list dominated by spinners – was considered highly likely to be in England’s XI this weekend.
There was better news for Afghanistan, with Rahmanullah Gurbaz in line to face England despite an injury scare in their own practice match against Pakistan at the Gabba on Wednesday.
The wicketkeeper and opening batter was struck flush on the left boot by a Shaheen Shah Afridi yorker and departed lbw for a golden duck, but the results of a scan have indicated “no bone fracture”.
He will be assessed in the next couple of days but is expected to face England, according to a brief Twitter update from the Afghanistan Cricket Board.
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