The Blues boss goes into the League One fixture with limited options.
Gavin Bazunu and Joe Morrell are both away on international duty, while Cowley has revealed he only has 14 senior professionals currently fit for the trip to Wycombe.
Pompey enjoyed some good news during the week after it emerged that both Clark Robertson (tendon) and Ells Harrison (ankle) are ahead of schedule in their rehabilitation from injury.
Ryan Tunnicliffe’s hamstring complaint is also not as bad as first feared, although he too won’t be available for the trip to Adams Park.
Meanwhile, Downing is making good progress on the hamstring injury he picked up in the Papa John’s Trophy defeat against Sutton on October 12.
Cowley has no need to throw the 30-year-old centre-half straight back into action, with Sean Raggett and Connor Ogilvie set to resume their central-defensive partnership against Wycombe.
However, he’s contemplating recalling the former Blackburn defender – who has made only three appearances this season – to his match-day squad earlier than expected so he has adequate cover during this time of need.
The Pompey manager told The News: ‘We’re waiting on Paul Downing and we may need to bring him in a week earlier than we anticipated, which will probably give us 14 or 15 (senior players).
‘We’ve got to be careful and this is the dilemma you get into.
‘Unfortunately, we’ve picked up some injuries that we didn’t want, but these have happened and sometimes you see a correlation or a pattern and you can say “right, we need to do more of this”, but Paul’s has been different, really.
‘For us, we never make excuses. The circumstances and situation that we find ourselves in, we see the opportunity and the positivity in that.’
Cowley added he could also be forced to call upon some of the youngsters who featured in the midweek Trophy win over Crystal Palace under-21s.
Harvey Hughes and Adam Payce made their full debuts in the win, while Harry Jewitt-White, Issy Kaba and Alfie Bridgman made appearances from the bench,
‘We had a long day with the academy on Wednesday, we were with them all day and they played a lot of football,’ added Cowley.
‘It was almost like a football marathon for them and I was coming away a little bit worried about them as they might be involved with us on Saturday.’
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