Craig MacGillivray has applauded Pompey’s age-defying central-defensive rock.
Matt Clarke and Jack Whatmough, each aged 22, are the foundations a League One-topping campaign has been constructed upon.
Between them they have amassed 213 appearances for the Blues – a remarkable figure considering their ages and position served.
As Kenny Jackett’s preferred centre-half partnership, their 13 outings together have this season yielded six clean sheets, with nine goals conceded.
It has aided the creation of the second-best defensive record in League One.
And the goalkeeper operating behind has been stunned by the maturity of the burgeoning Clarke and Whatmough pairing.
MacGillivray said: ‘For such a young age, the pair of them are unbelievable. Unbelievable.
‘There are a lot of young players out there who have all the ability, but maturity-wise are not there.
‘Whereas Clarkey and Whatty are babies and perform with maturity. I think it is incredible, I had to double take when I was first told about their ages.
‘Their ability is there, but it is their maturity which got me, how grown up they are and how well they read the game and don’t get sucked into an occasion. They are so level-headed.
‘Normally when you see a young lad with no experience it can be difficult, but both gel very well with their mindsets – and their maturity levels are second to none.
‘Look at the attributes they’ve got, they have everything in abundance. It’s all up to them now to keep hold of their shirts, keep working hard in training and putting in the performances.
‘I am sure if they keep their heads down then they’ll have a very, very good career.’
Clarke has racked up 135 appearances and scored eight times since his August 2015 debut in the season’s opener against Dagenham & Redbridge.
Whatmough, who is aged 35 days older, made his bow in November 2013 against Southend and currently has 78 outings and one goal.
Jackett initially matched the duo from March last season for a nine-game spell, but injury to Whatmough split them up.
However, they have been reunited this season, emerging as the Blues boss’ favoured pairing once again and producing a string of eye-catching displays.
Meanwhile, Christian Burgess has still featured six times alongside Clarke during the campaign, conceding seven goals in the process, to bolster competition.
And MacGillivray continues to be impressed by the young duo primarily at the heart of the Blues’ promotion push.
He added: ‘If you have a good relationship with your back four – and the whole team in general – and communicate together, then your job is easier as a goalkeeper.
‘The pair of them are up there definitely in terms of the best partnership in the division.
‘I am not great when it comes to singling out defenders, but from what I’ve seen this season they’re definitely up there, 100 per cent.’