Big deals are unlikely for Kenny Jackett’s men with the salary cap and restrictions working against them, but there could still be a late deal or two in the pipeline.
Pompey will also be keeping a close eye on what their promotion rivals are doing today too, with League One expected to see a number of loan moves.
Sunderland are unlikely to do much business on incomings today, having completed the signing of Ross Stewart last night from Ross County.
However, Stewart’s arrival should be the trigger for Sunderland to let Grigg leave. The 29-year-old has been a huge disappointment since his high-profile move two years ago, and there are a host of League One sides interested in taking him, including Oxford United and Shrewsbury Town.
Johnson added: "Will wants to play every game, he wants to be closer to his family who are in Stafford, and we are probably going to have to accommodate that on this occasion if we get that extra man in."
Shrewsbury could be one of the busiest League One teams today, as they look to add three or four players to their ranks before the window shuts, similar to Oxford.
At the top end of the division, Peterborough United are hoping to hang on to their star striker, while Doncaster Rovers’ business has all but been done – though they are braced just in case they get a bid for one of their main defenders from Preston.
Hull City could be set for a quiet day with the promotion favourites having already completed a lot of their business, though Gillingham boss Steve Evans – no stranger to a transfer or two – is hoping to get a number of players in to bolster his squad.
It promises to be a busy end to the window, which shuts at 11pm. Here’s a list of some of the big deals that could go through in League One before the deadline.
5. Charles Vernam
Burton Albion attacker Vernam could be on his way to a League One club today. Grimsby were interested in the former Derby County youngster who has come back into the starting line-up after injury, playing in 11 of Burton’s last 12 league games. Photo: Pete Norton
6. Oxford United
Karl Robinson, Manager of Oxford United, is hoping to add two wingers and a left-back to his squad before the 11pm deadline. And maybe a high-profile striker too... Photo: Alex Burstow
7. Gillingham
Boss Steve Evans, fresh from his side's 2-2 draw at Sunderland on Saturday, is hoping for fresh faces today. “We are in the mix with two or three,” he said, on Saturday. “We have to bring two or three players in." Photo: Dan Mullan
8. Scott Twine
Twine could be on his way out of Swindon Town today. He caught the eye on loan at Newport, chipping in with seven goals and five assists before being recalled to the County Ground. The 21-year-old is out of contract in the summer and Luton, Reading, Brentford, Bournemouth and QPR have been linked with the forward. Photo: Pool