Prior concern a worry for England cricket captain Cook
England's Alastair Cook bats during the third ODI against Sri Lanka at Old Trafford on May 28, 2014 - by Andrew Yates
Established Test gloveman Prior was dropped from the side during the team's 5-0 Ashes thrashing in Australia but it had been expected the 32-year-old would force his way back into the team for next month's two-Test series.
However, the 32-year-old Sussex stumper has since suffered an Achilles injury which has restricted him to just two first-class matches this season, both at the start of April.
It had been hoped Prior would return for Sussex's First Division County Championship match away to Middlesex at Northwood but rain caused the fixture to be a washout.
Even before no play was possible on Thursday's final day it was decided Prior would be better off undergoing a training session with England wicketkeeping coach Bruce French.
Afterwards, Prior told his Twitter followers: "Hard session with frenchy today, as always, and so far the injury has responded very well!"
Prior is now set to return to Sussex duty in Friday's Twenty20 match away to Glamorgan, although it is possible he may play as a batsman only.
Even if he is behind the stumps, keeping wicket for 20 overs is no sure fire way of assessing his fitness for the rather more onerous task of donning the gloves for the 90 overs of a Test match day.
And with doubts over the batting ability of Jonny Bairstow, who replaced Prior during the Ashes, and the keeping skills of Jos Buttler, England's one-day gloveman, the selectors face a tricky decision ahead of next week's squad announcement for the first Test at Lord's on June 12.
"It is a big concern," Cook, speaking after England's stunning 10-wicket win in the third one-day international at Old Trafford on Wednesday, said of Prior's fitness.
"He's incredibly frustrated, because Achilles injuries are hard to heal. He's a big part of our plans, but we can't rush a guy back. That wouldn't be fair on him or to the England team."
Buttler, for all the worries about his wicketkeeping, could be behind the stumps come the first Test, although Cook is well aware of the need for the 23-year-old Lancashire keeper to sharpen up his glovework.
"He's nowhere near the finished article with his wicketkeeping. But just watch him practise -- you will see him put the hard yards in -- and that will keep going the right way, no doubt."
Meanwhile a see-saw one-day series moves on to Lord's on Saturday, with England 2-1 up in the five-match contest after skittling out Sri Lanka for just 67 in Manchester -- Sussex paceman Chris Jordan taking a career-best five for 29.
That performance came just days after England had themselves been dismissed for 99 at Chester-le-Street, a collapse Cook could only watch as the opening batsman missed that match with a groin strain.
"There is no need for that -- you can't blame that on inexperience at all. It wasn't pretty viewing," he said.
"What it did show against a side like Sri Lanka is that if you give them an inch they will take a mile."
And that is what England did when turning the tables at Old Trafford.
"As a sportsman, you have to spend your time ... looking at the next challenge and bouncing back from the bad stuff," explained Cook. "I think we caught Sri Lanka napping a little bit."