The Pompey skipper missed last weekend’s opening day 3-3 draw against Sheffield Wednesday due to a foot injury.
The 28-year-old central defender damaged his plantar fasciitis in the 2-0 pre-season defeat to Coventry a fortnight ago, with the Blues boss revealing the defender would be sidelined for a ‘short-time’.
However, Cowley is optimistic of a return for Robertson on Saturday after he reported for training this week.
Predicted Portsmouth XI v Cheltenham: changes expected to side that beat Cardiff so handsomely - but attacking duo could keep places and defender set to return
Portsmouth boss Danny Cowley makes transfer admission as former Luton and Millwall midfielder edges closer to Fratton Park exit
Portsmouth transfer news: Blues youngsters attracting interest but Danny Cowley has no desire to cash in just yet
Former Portsmouth keeper Alex Bass suffers tough night on and off the pitch as he makes Sunderland debut following Fratton Park exit
League One latest: Oxford land former Pompey striker target from Swansea as Sheffield Wednesday bemoan exciting duo's move to Brentford and former Peterborough boss criticises club
Now the head coach just has to make a decision on who he will go with, after pairing Sean Raggett with Michael Morrison last time out.
The visit of the Imps should also see Louis Thompson feature after he failed to finish last weekend’s draw at Hillsborough.
The midfielder was replaced by Ryan Tunnicliffe in the 90th minute, with Cowley admitting the former Norwich man was taken off with cramp as a precautionary measure.
The game against the Owls saw Pompey operate without Joe Morrell, who is currently recovering from a hernia operation.
He will miss Saturday’s visit of Mark Kennedy’s side.
However, Cowley is confident 27-year-old Thompson won’t be joining him in the new-look Fratton Park stands and will be fit to face his former side.
Speaking to The News ahead of Saturday’s fixture, the Blues boss told The News: ‘Louis (Thompson) is fine, he's a strong boy.
‘We went into 80 minutes with him, we don’t always get that far into the game with Louis but he was playing such an important role and he just felt a bit of cramp.
‘He’d just cramped and he wanted to go back on but for us it’s to never to take that risk particularly with Joe Morrell and the position he’s in coming back from his operation.’
Jayden Reid (hamstring) remains out for the Blues – as is Denver Hume as he continues his recovery from a back complaint.