Portsmouth's Thompson ruled out for '˜several' weeks
Nathan Thompson is expected to be sidelined for '˜several' weeks.
Pompey's right-back damaged the hamstring in his left leg during the second half of the Boxing Day defeat at Gillingham.
The tear occurred while overstretching during a surge infield with the ball as the Blues attempted to find a way back into the game.
Thompson subsequently had to be helped off by Pompey head physio Bobby Bacic, along with a member of the Gills' medical team.
With Kenny Jackett's three substitutes having already been employed, it meant the visitors had to see out the final 15 minutes with 10 men, ultimately losing 2-0.
And Pompey's boss is anticipating the tough-tackling defender will now be out of action for a number of weeks.
Jackett said: '˜Obviously Nathan has a hamstring, so I will be very much surprised if he plays against Fleetwood.
'˜Other than that, we will see where everybody is, I expect everybody to be okay and we have players to rotate if we need it.
'˜With Nathan it's a hamstring injury. It looks like it will be several weeks out, that's the first impression.
'˜But we doÂ have the squad numbers.'
Thompson's absence is a blow to the Blues, having been a crucial performer during their tenancy at the top of League One.
He has amassedÂ 21 appearances this season and remains Jackett's first-choice right-back when available for selection.
Anton Walkes is the obvious replacement for Saturday's trip to Fleetwood and beyond as the Blues seek to cope without Thompson.
The versatile former Spurs man has been utilised in a variety of roles at Fratton Park, including as a holding midfielder and centre-half.
Yet he is seen as Thompson's natural deputy, most recently lining-up at right-back in the Checkatrade Trophy success over Arsenal under-21s earlier this month.
Walkes also stood in for Thompson during a six-game spell at the start of the start of the season, when Jackett's first signing collected an injury in the opening match against Luton.
New recruit Andy Cannon has operated as a right-sided full-back in the past for Rochdale, before his Fratton Park switch.
Yet he has been earmarked for an attacking role when linking up with his new Pompey team-mates on January 1.
Thompson, who has made 61 appearances since joining from Swindon on a free transfer in June 2017, is out of contract this summer.