The attacking left-back was Danny Cowley’s first signing as head coach in June 2021, arriving for an undisclosed fee from Bromley.
However, Vincent has been blighted by issues surrounding a stress fracture to his left shin since the second training session of pre-season.
Although there was a fleeting two-game presence on the first-team bench in November, he has been unable to play this campaign.
Encouragingly, the 19-year-old returned to the training pitch more than a week ago.
And Cowley is hoping the latest comeback will not be aborted like the others.
He told The News: ‘Liam’s has been training with us for more than a week now, which is good.
‘We are just taking it very, very gradually due to the nature of the stubbornness of the injury.
‘It’s a stress fracture of the tibia, which is the main weight-bearing bone, and we are hopeful this time will be fine.
‘The scan suggests the injury is clear and we can now push on and gradually increase his training so we can build his robustness to be able to cope with the rigours of full-time football.
The plan was to sign Liam and then to find a playing pathway, that obviously hasn’t been possible due to his injury.
‘He’s a very young player, we might still loan him out this season. It’s down to where we are with the squad.’
It has been almost nine months since Vincent’s Fratton Park arrival.
Originally pencilled in to offer youthful cover for Lee Brown, his rival has since departed with left-sided defenders Connor Ogilvie and Denver Hume subsequently joining.
Vincent has also missed out on the opportunity to feature in Pompey’s Papa John’s Trophy campaign, a competition which lends itself naturally to young players.
Now there’s nine weeks of the season remaining as he maintains his rehabilitation.
Cowley added: ‘It’s one step at a time with Liam.
‘At the moment we don’t want to get ahead of ourselves, so what we’d like is to get a consistent run of training and find some rhythm, certainly for the next 5-6 weeks.’
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