Michael Appleton admits Pompey would have struggled to cope with the injury problems that West Ham have dealt with this season.
The Hammers have a big squad and plenty of quality but it has been stretched by a succession of injuries that have affected results in recent weeks.
The Pompey boss said: ‘If you look at the strength in depth that they have, it’s been tested over the past month or so. I’d hate to think of us as a squad, how we would deal with that same situation.
‘It doesn’t bear thinking about. But they have dealt with it reasonably well.
‘Sam (Allardyce) has got experience to bring to the table and has had success as a manager, which rubs off on some of his players. That’s why they are up there.
‘It’s going to be a good game tomorrow. It’s a match-up that most people are looking forward to this weekend.
‘We’ve got good home form and they’ve got good away form.’