The Pakistan Cricket Board say they are confident Shaheen Afridi will be fit to play at the T20 World Cup.
The fast bowler is missing the Asia Cup in the UAE because of a posterior cruciate ligament injury sustained while fielding in a Test match against Sri Lanka in July.
He had been with the squad in Dubai, and watched on from stands as his team were beaten by India on Sunday night.
Now he has departed to London, where he will continue his rehabilitation.
It is 55 days until Pakistan start their T20 World Cup campaign against India at the MCG in Melbourne.
"Shaheen Shah Afridi requires uninterrupted, dedicated knee specialist care," said Dr Najeebullah Soomro, the PCB's chief medical officer.
"London offers some of the best sports medical and rehabilitation facilities in the world. In the best interest of the player, we have decided to send him there.
“The medical department will receive daily feedback on his progress while in London and we are confident Shaheen will return to full fitness before the ICC Men’s T20 World Cup.”