Pompey secured the signing of Marlon Pack earlier in the window as he marked his return to Fratton Park following Cardiff exit at the end of the season.
Meanwhile a deal for former Preston defender Joe Rafferty is also apparently close.
The Blues boss is still requiring plenty of improvement across the pitch with at least three new strikers currently top of his wishlist as well as further strengthening in defence and in goal.
But could Cowley still turn to any free agents currently available in the market this summer?
We’ve taken a look at the top 10 players still without a club following their exits from League One clubs.
Here’s what we found.
1. Massimo Luongo
The Australian played a pivotal role in Sheffield Wednesday’s midfield last term alongside Barry Bannan. However, he rejected a new deal to stay at Hillsborough and is reportedly on trial with Championship side Reading. Photo: George Wood
2. Connor Wickham
The striker penned a deal until the end of the season in January with MK Dons, where he found the net just once in 12 outings. Like Luongo, the 29-year-old has also found himself on trial at Reading as he seeks his next move. Photo: Pete Norton
3. Callum Johnson
Following the end of his two-year deal at Fratton Park, the right-back was released by the Blues after his loan spell with Fleetwood. The 25-year-old remains without a club but has recently been linked with a move to Charlton. Photo: Nigel Keene
4. James Norwood
Norwood was released by Ipswich following the end of his three-year deal with the Tractor Boys. The 31-year-old scored 27 goals in 77 league outings for the Blues and has also been linked with Pompey, Oxford United, Preston and Wigan after his exit. Photo: Lewis Storey