Guy Whittingham revealed Jed Wallace’s endless energy kept him on the pitch to fire Pompey’s leveller at Doncaster.
The 18-year-old struck his third senior goal in the 1-1 draw at the Keepmoat Stadium.
He slotted home a loose ball 15 minutes from time to earn the battling Blues a point.
But the teenager was among those struggling to cope with a dreadful playing surface.
And had it not been for his fitness and work-rate, he may well have been substituted as Pompey switched to wing-backs in their search for an equaliser.
Caretaker boss Whittingham said: ‘We had a few discussions but we still felt he was the one to give us that bit of energy as a wing-back, so it was a good decision to keep him on.
‘He probably had his best game for us at Leyton Orient, and while I wouldn’t say that was his worst game for us, he struggled a bit at times.
‘But the good thing with Jed is he is full of running and energy, whether he is having a good time on the ball or not.
‘He kept going and the fans always appreciate that. It’s what you have to do, even when things aren’t going well.’
Having missed two decent chances at Leyton Orient, the youngster produced a cool finish when it mattered.
Whittingham said: ‘Jed was supposed to be wing-back at the time and ended up in the middle of the box but that’s the asset he has got.
‘David Connolly was looking to get a shot off but the ball bobbled, went under his foot and fell nicely for Jed, who took it well.
‘It was his best pass of the day!’
– STEVE WILSON