Pompey are sweating on the fitness of Dave Kitson ahead of their trip to Brighton.
The striker bruised his foot in the defeat to Hull and sat out training yesterday.
Definitely out is Ricardo Rocha, who was today set to receive the results of a scan on his injured hamstring.
That leaves Ibrahima Sonko vying with Hermann Hreidarsson to replace him in central defence.
Joel Ward will get a recall at right-back in place of the suspended Greg Halford.
As ever, Michael Brown and Richard Hughes won't feature.
Cotterill said: 'It's a wonderful competition and I'm looking forward to it.
'The FA Cup has maybe lost a bit of what it has had over the years but it's a wonderful competition.
'I don't know how Brighton will look at the game. I saw them against FC United and they made a lot of changes.
'Is it a distraction? It doesn't make a difference. A game is a game is a game.
'We didn't look like we lacked confidence in the last match. We looked good against Hull and definitely deserved to win. The confidence is there.'
On-loan Chris Wood has been given permission to feature for Brighton tomorrow.
The West Brom striker has extended his Withdean loan and will be in the squad for the visit of Pompey.
However, he could find himself on the bench following Ashley Barnes' goal-scoring entrance against Exeter on Monday.
Meanwhile, winger Craig Noone is cup tied, having played for Plymouth in an earlier round. Veteran Mauricio Taricco will again deputise for the suspended Inigo Calderon.
Seagulls boss Gus Poyet said: 'We will change a few players because we have got to make sure that the players who are not starting at the moment are still ready, because they will be needed.
'I promise that I will not change the team too much, but there will be some changes.
'We've had a couple of difficult rounds so far, taken to replays by Woking and FC United of Manchester.
'Let's hope we can finish this one at the Withdean in 90 minutes. I don't know Portsmouth's approach, but it's up to us to keep playing our way.'