Kenny Jackett is weighing up a switch to wing-backs.
The Pompey boss believes he now has the versatility in his squad to employ a change in formation.
Deadline day proved a final frenetic round of action before the window’s close with four players signed and four men leaving Fratton Park.
Left-back Damien McCrory, midfielder Stuart O’Keefe, winger Matty Kennedy and striker Oliver Hawkins made it nine signings for Jackett since his arrival.
On top of that Jackett is beginning to see his injury problems clear.
His men take on Rotherham tomorrow in their first outing since the transfer window closed.
The Blues manager has continued with the 4-2-3-1 formation largely employed by Paul Cook in his time at the club.
Jackett feels the balance of his side needs to be right before looking at three at the back.
He said: ‘It’s something I wouldn’t hesitate to use if I thought it was right.
‘Whatmough has done well while Clarke and Burgess were pretty much ever-presents last season.
‘Thompson’s an experienced defender as well.
‘I did mention early on that I thought it could develop into a strength of ours.
‘We didn’t have the players fit early on, though, so we’ll see.
‘We’ll have to make sure they are up to speed first and then, at the right time, I’m sure it could come into play.
‘If it can be a strength of your team it does help you to get another attacking player into a forward area.
‘We haven’t had the players. You can do it if the players are right, fit and the combinations are right.
‘You need the players ready, capable and the right mix and complement around them.
‘You can do it with a few training sessions if you need to as well.’
After the recent business, there’s a different look to the Pompey squad as they attack the second month of the campaign in front of the Sky Sports cameras tomorrow.
Jackett felt he needed to bring the average age down, as he looks to leave his imprint on the Pompey set-up following his June arrival.
He said: ‘Right from when you take a team at day one it’s always evolving.
‘For myself, I thought it did have to evolve from the end of last season on the age of the squad and the age of the team. That’s just how I felt about it.
‘It has moved on and it has to move on quickly.
‘While you are evolving and improving you need to win games of football as well.
‘You have to do it from day one. You can’t just say you need x amount to get there. It needs to be straight away.
‘It’s your team straightaway but, at the same time, it does take time to evolve and be a really strong unit in this division.
‘Really, though, how long does it take? It has to be instantly.’