The Blues’ skipper was ruled out of Saturday’s trip to Sheffield Wednesday after injuring the plantar fasciitis, which is the bottom of the foot.
According to Cowley, the injury struck following the recent 2-0 friendly defeat to Coventry at Fratton Park.
As a consequence, Pompey intervened last Monday evening while Michael Morrison was heading to Huddersfield to complete a transfer.
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The veteran centre-half subsequently deputised for Robertson in Saturday’s 3-3 draw at Hillsborough, despite having just 45 minute under his belt from pre-season.
Indeed, the performances of Morrison and Sean Raggett at the heart of the Blues’ defence earned praise from the head coach.
And Cowley believes Robertson could be back in time to face Lincoln next Saturday.
He told The News: ‘He’s got a small tear to the bottom of his foot, which is really frustrating for Clark, I really feel for him.
‘He has done every training session, played every game, been in brilliant shape physically, and felt a bit of tightness after the Leyton Orient game.
‘We were told (by his medical team) that we didn’t have to worry about it, but it has become something more.
‘It’s a small tear and we are hopeful he will be back for Saturday against Lincoln.
‘That sped up the process of recruiting another centre-half, so we brought Michael (Morrison) in at short notice.
‘I thought he did great on Saturday. Wow. To be able to play off nothing and to that level. He and Sean Raggett were lions.’
Raggett himself received an injection on Wednesday to relieve a back problem which has been troubling him since their Spanish summer training camp.
Meanwhile, Haji Mnoga served as the back-up centre-half on Pompey’s bench against the Owls, albeit wasn’t called upon.
Yet, when Robertson is been declared fit, Cowley will be looking to send out Mnoga on loan to aid the 20-year-old’s development.
He added: ‘We always knew that we probably had to add an extra defender to the group.
‘Where we are as a club, it’s absolutely right to try to give Haji as much game time. We are really committed to developing the young players.
‘It was great for him to be involved on Saturday, but we also know we need to get him regular games if he’s going to progress and develop the way we want him to.
‘We’ve brought Michael in, so once we get a fit group of defenders then hopefully that will create an opportunity for us to allow Haji to go and get some more game time.’
A message from the Editor, Mark Waldron
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