And the Blues defender is ready to continue that bid to be in Kenny Jackett’s starting XI against Rochdale this week.
Whatmough is going head-to-head with Tom Davies for a starting berth in the League One curtain-raiser at Fratton Park on Saturday.
The pair played alongside each other in the middle of defence in the final warm-up game at Crawley on Saturday.
Jackett’s side picked up a 2-1 win at Broadfield Stadium as Harry Kewell’s side posed a stern physical challenge.
Christian Burgess missed out with a slight calf strain but is set to return this weekend.
With Burgess likely to start on the right of the central two, that leaves one spot up for grabs at the back.
Whatmough wants to do everything he can to get the nod in front of his team-mate.
He said: ‘Burge didn’t play but will come back in if he’s fit and that’s understandable.
‘We probably are (playing for one place). I’ll do everything I can this week to be the one to play alongside him if I can.
‘I’ve played on the left of the two nearly every game so I’m comfortable there.
‘I feel comfortable playing on my left foot and coming back on the right side. I feel comfortable playing there.
‘I don’t think any position is secure. You’ve got to do whatever you can do to keep that shirt if you’re there.
‘If you’re not there you’ve got to do whatever you can to get it.
‘That’s what football’s like. It’s very competitive. Hopefully I’ve done enough.’
Davies has picked up more playing time than Whatmough in Pompey’s warm-up games.
The defender appeared to be on his way out of the club with Paul Cook keen to offload him before his exit.
But the 25-year-old was offered a stay of execution by Jackett and has grabbed his opportunity in pre-season.
Davies has picked up minutes against Salisbury, Hawks, Bognor Bournemouth and Crawley.
Whatmough has seen playing time against Salisbury, Poole, Hawks, Newport and Kewell’s men.
The Gosport lad feels it’s been a mixed period for him - but remains confident in his ability to deliver at League One level.
Whatmough said: ‘Pre-season could’ve been better and it could’ve been worse.
‘I probably would have liked to have played a bit more.
‘For whatever reason, I haven’t had too much but I got the start against Crawley and hopefully I did well enough to play against Rochdale.
‘You have to back your own ability whatever league you’re in.
‘That’s something I do whether it’s on the left side or right side of the middle.
‘I have a lot of confidence in my own ability.
‘So I’m looking forward to the season ahead.’