Sohail Tanvir, the left-arm seamer, has been ruled out of Pakistan's World Cup campaign after failing to complete a full rehabilitation from surgery for a knee problem that has dogged him for two years. He will be replaced by the promising young left-arm fast bowler Junaid Khan.

A PCB medical panel, after looking into a management report, said that though "the recovery from a knee operation was good, during the [New Zealand] tour it was observed that quick movements and pickup with weight particularly on the operated knee is hindering his mobility and requires him to take a few extra steps to balance himself before throwing. The medical team and team management have opined that Sohail Tanvir still requires time to attain 100% fitness before he can compete at international level."

Tanvir returned to international cricket on Pakistan's recent tour to New Zealand, where he played in five of the six ODIs. Though he bowled some good spells at the death, he looked generally rusty, picking up just 4 wickets and going for over seven runs an over. Pakistan won the series 3-2.

His batting, however, seemed to have improved, as evidenced by an audacious, unbeaten 14 off 6 balls to seal the fifth ODI. Until this series, he hadn't played for Pakistan in an ODI since May 2009 and at one stage, the knee problems threatened to end his career.

His misfortune, however, is to the benefit of Khan, who has been close to a national call-up for nearly a year now. The 21-year-old emerged at about the same time as Mohammad Amir, playing alongside him at U-19 level for Pakistan. He has been a consistent wicket-taker at domestic level, in all forms of the game, and given that he plays most of his cricket for one of the traditionally weaker regions, Abbottabad (in the Khyber-Pakhtunkhwa province), it is an impressive record.

Former Test spinner and selector Iqbal Qasim, who first picked him for junior level, believes he has immense potential and was impressed initially by his pace as well as stamina. Some observers, at that early stage, felt Khan might make it to the national side before Amir, though he hasn't, they say, developed as swiftly. But he has been playing for the Pakistan A side regularly now, and is familiar at least with where Pakistan will play their first game of the World Cup: last September he took nine wickets in a 'Test' against Sri Lanka A in Hambantota, where Pakistan will take on Kenya on January 23.

The PCB said the ICC's technical committee had approved the request.