An untimely bout of what is thought to be chickenpox has left Mohammad Amir's World Cup hopes hanging on by the thinnest of threads.

Amir missed the second ODI against England in Southampton because of what team officials said was a viral infection and he is set to miss the third game in Bristol tomorrow as well. It has now emerged that the infection is likely to be chickenpox. Amir is understood to be in London with his family and not with the team currently.

How long it will take him to recover is not clear at the moment. But even if it is a week from when he originally fell ill, it leaves him with a monumental task to break into Pakistan's 15-man squad. There are only two ODIs left in the series, on Friday and then Sunday. It is thought if he doesn't recover in time for Friday's game, it would be close to impossible for him to make it to the squad.

Amir was not part of Pakistan's original World Cup squad but because teams have till May 23 to make changes, it was thought his initial exclusion was not final. He was brought along as part of the squad to face England and the series was very much seen as an opportunity for him to make a case for himself for World Cup selection.

He was in the XI for the first ODI at The Oval last week but the match was abandoned after 19 overs in which Pakistan batted first. He fell ill on Friday, ahead of the second ODI on Saturday.

If he doesn't make it, it will be the third World Cup he has missed since making his international debut in 2009 - he missed out in 2011 and 2015 because he was serving a five-year ban for his role in the Lord's spot-fixing scandal of 2010.

Amir's wicket-taking form in ODIs since the final of the Champions Trophy in 2017 has been poor. He has only five wickets to show in that time in 15 ODIs (including the washed out game at The Oval). He hasn't leaked runs especially, however, and his economy rate of 4.58 in that period (5.28 if you exclude Zimbabwe and Hong Kong) assumed greater relevance in light of Pakistan's bowling troubles in Southampton, where they conceded 373.

Specifically the death-overs bowling was poor but the fast bowling generally since Pakistan have landed in England has become a growing concern for Mickey Arthur and Sarfaraz Ahmed. They have options ahead of tomorrow's ODI and Junaid Khan is likely to return, as might Mohammad Hasnain.

Osman Samiuddin is a senior editor at ESPNcricinfo