Pietersen forced home by rib injury
Each time he played an attacking shot he winced in pain, and he then left the field during the Pakistan innings. The England medical team had hoped that Pietersen would be able to stay for the remaining three one-day internationals following a cortisone injection, but it has not proved effective.
Dr Peter Gregory, the ECB's chief medical officer, said: "Due to a series of events that aggravated a previous rib problem during practice and the first two one-day internationals Kevin is returning home to the UK and will play no further part in the one-day series.
"Scans taken after the first one-day match showed no fracture but demonstrated a stress lesion and despite passing a fitness test ahead of the second one-day match Kevin suffered intolerable pain throughout. A stress lesion of this nature is likely to require four to six weeks rest but it is expected that Kevin will make a full recovery in time for the tour to India in March next year."
Pietersen added that he wouldn't want to be a burden on his team-mates: "It's very disappointing to be leaving the England team at this time as I was looking forward to a strong one-day series. I hate missing matches and despite trying to play the first couple of one-day games the pain was just too great. I certainly wouldn't want to let my team-mates down due to injury whether it is with the bat or in the field so the only choice available to me is to rest the injury with a view to a full recovery in time for India."
Pietersen's withdrawal is a huge blow to England after he made an explosive start to the one-day series, making 56 off 39 balls in the first match and 28 off 27 in the second. He has rapidly developed into England's key one-day batsman during a 12-month period that earned him the ICC's One-Day Player-of-the-Year award.
No replacement will be added to the squad for the remaining matches and Pietersen's departure opens up an opportunity for Ian Bell to fit into the middle order for the next match, in Karachi on Thursday.