The Big Bash League will feature a second Afghan star this summer after Brisbane Heat announced the signing of 17-year-old spin sensation Mujeeb Ur Rahman.

Afghanistan's Rashid Khan lit up the BBL last season with the Adelaide Strikers and he will be joined by his countryman and fellow leggie in BBL|08 after the Heat secured Mujeeb as a replacement for Pakistani spinner Shadab Khan.

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With Shadab unavailable due to international duty, the Heat have brought in the teenager as their second overseas signing alongside Kiwi veteran Brendon McCullum.

Aged just 17 years and 198 days, Mujeeb is the youngest player to ever sign a full BBL contract.

A self-taught cricketer who learnt to bowl by watching YouTube videos, Mujeeb has bamboozled some of the best batsmen in the world since he made his international debut last December and became the first male born this century to play at the highest level.

He's taken 44 wickets in just 23 ODIs at an average of 18 and economy rate of 3.84, vaulting him to 10th on the ICC's world rankings, and he's also taken nine wickets at 15 in seven T20s for Afghanistan.

Seventeen of Mujeeb's ODI wickets came during Afghanistan's dream run in the ICC's World Cup Qualifier tournament this year, an equal tournament-leading haul that included 4-43 in the final as the Afghans won through to next year's World Cup in the UK.

He also fired against some of the best batsman in the world during the IPL this year. Having been bought for A$785,000 by Kings XI Punjab, Mujeeb took 14 wickets including that of Indian star Virat Kohli, bowling him in the spinner's second match.

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He even imparted some knowledge on Kings XI teammate and Indian spin star Ravi Ashwin, who praised the teenager's maturity and knowledge of the finer points of spin bowling.

"He has that innate intelligence," Ashwin said.

"He is quite smart. He is a self-made cricketer. Most of the Afghans are self-made and self-taught. It just becomes that much easier then."

The Heat have one more spot on their BBL roster to fill ahead of their tournament opener against the Strikers at the Gabba on December 19.

Brisbane Heat

Current squad: Max Bryant, Joe Burns, Ben Cutting, Brendan Doggett, Sam Heazlett, Marnus Labuschagne, Josh Lalor, Chris Lynn, Brendon McCullum (NZ), James Pattinson, Jimmy Peirson, Jack Prestwidge, Matthew Renshaw, Alex Ross, Mark Steketee, Mitch Swepson, Mujeeb Ur Rahman (Afg)

In: James Pattinson (Renegades), Mujeeb Ur Rahman (Afg), Jack Prestwidge

Out: Shadab Khan (Pakistan)

Roster spots to fill: one

Internationals signed: two