Pakistan all-rounder Abdul Razzaq has been forced to miss the World Cup after injuring his knee in training.
Razzaq, who will not return to action for at least five weeks, has been replaced in the squad by Azhar Mahmood.
Pakistan confirmed Umar Gul will play after recovering from a shin injury but doubts remain over new-ball pair Shoaib Akhtar and Mohammad Asif.
The duo, who failed drug tests last year but were subsequently reinstated, must submit to more tests this week.
The rest of the 15-man squad, plus five stand-by players, have already been officially tested by doping officials.
Shoaib and Asif both tested positive for nandralone in September but were cleared after claiming they had not knowingly taken the banned substance.
"I am very confident that Akhtar and Asif will be available before our first game"
Reports suggest the pair have had private tests while in London for treatment on their injuries. Shoaib has knee and hamstring trouble while and Asif has an elbow problem.
Pakistan leave on Thursday for Jamaica, where they open their campaign on 13 March against hosts West Indies, before facing Zimbabwe and Ireland in Group D.
"We still have a lot of time and I am very confident that Shoaib and Asif will be available before our first game," captain Inzamam-ul-Haq told a media conference.
"Obviously our chances would decrease if they could not make it."
Gul made an immediate impact at international level, claiming 25 wickets in his first five Tests, including 5-31 in his maiden match against India in 2004.
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A back injury sidelined him for the whole of 2005 but he captured 18 wickets in four Tests in England last summer.
"Gul is fine now and has been bowling in the nets - his availability is a big boost," said coach Bob Woolmer.
Razzaq was hit on the knee by a ball during practice on Monday and doctors have advised him to take three weeks rest, followed by another two to three weeks of physiotherapy.
"Initial assessment of the injury revealed apartial ligament tear and bone bruising," said a statement.
"Razzaq's knee was subsequently put in plaster for three weeks."