New-recruit Ryan Williams has been ruled out for two weeks through injury.
The Australian international is not present on Pompey’s pre-season tour to Dublin after last week pulling his quad in training.
The problem is likely to rule him out of the opening four friendlies of the Blues’ summer schedule.
These include UCD (Wednesday), the Hawks (July 13), the Rocks (July 16) and Stevenage (July 20)
It’s a cruel blow for Williams, who linked up with his new team-mates last week following a free-transfer arrival from Rotherham.
He represents the notable absentee from Kenny Jackett’s 23-man squad which checked into the Portmarnock Hotel on Sunday.
With Luke McGee left behind and Jack Whatmough injured, Jackett has drafted in Academy graduate Joe Hancott to bolster numbers.
Those present in Dublin include latest signing Ross McCrorie, who sealed a season-long loan from Rangers on Friday afternoon.
He is among six new faces, with James Bolton, Ellison Harrison, Paul Downing and Sean Raggett also present for the six-day stay in the Republic of Ireland.
Also in attendance is Matt Casey, who recently penned a new deal and is regarded by Jackett as his fourth central defender.
Meanwhile, Ronan Curtis has joined the squad, after granted additional time off following international duty with the Republic of Ireland earlier in the summer.
Pompey’s friendly programme kicks off at League Of Ireland Premier Division side UCD on Wednesday (5pm).
Jackett’s men, who return to England on Friday, will then face the Hawks on Saturday, July 13.