It’s a daunting prospect, given the midfielder’s importance to the team.
But it’s something the Blues will need to get their head around fast as a knee injury looks set to keep the 31-year-old out until perhaps the start of April.
It’s a scenario Pompey have faced three times already this season, with a hamstring problem and two separate red card incidents forcing the former Cardiff and Bristol City man to watch on from the stands.
But with the Blues looking to avoid their lowest League One finish since their 2017 return and new head coach John Mousinho wanting his best players available to him to ensure a strong finish to the season, Pack’s absence will be sorely felt.
So what are Mousinho’s midfield options going forward? Here, we have a look.
1. Joe Morrell
There's no doubt about it, the Welshman has consistently been the pick of Pompey's midfielders since his return from the World Cup. A stand-out performer in the Blues' engine room, he has the ability, experience, energy and leadership skills to be the main driving force in this key area of the pitch. That was evident last season following his summer move from Luton, and there's no reason why that can't be the case in Pack's absence. Can excel in both a 4-3-3 or a 4-2-3-1 formation. Photo: Jason Brown
2. Louis Thompson
The 28-year-old is another player who can ensure the blow of losing Pack can be cushioned. Indeed, his experience and calmness in the midfield battle ground, plus his ability to drive the team, won't be lost on new head coach John Mousinho. His versatility will also be key, with the former Norwich and MK Dons made able to play in a midfield two and three. After enduring a long injury lay-off himself this season following a broken leg, Pompey will need to manage Thompson's game time and know when to use him, though. Photo: Jason Brown
3. Ryan Tunnicliffe
The way the midfielder has transformed his season has been remarkable. Written off by many at the start of the season and tipped to leave Fratton Park, the 30-year-old has now made 24 appearances in all competitions. Has started six of John Mousinho's seven games in charge, too, and looks set to add to that in Pack's absence. It's the perfect opportunity for the midfielder to earn a new deal at Fratton Park, if he wants one, with his current contract expiring at the end of the season. Photo: Jez Tighe
4. Harry Jewitt-White
The 18-year-old was recalled from his loan at Gosport Borough recently so that John Mousinho could take a closer look at him. That led to the youngster making his league debut for the Blues as a substitute in the 2-1 defeat at Peterborough. He's not been involved in a Pompey match-day squad since, demonstrating his place in the pecking order. But with Tom Lowery and Jay Mingi not yet fit to return, the chances are Jewitt-White could at least make the bench for next Saturday's home game against Cheltenham. Photo: Jason Brown