Pompey are approaching the end of what has been a long and gruelling campaign.
Their Checkatrade Trophy triumph and a run in the FA Cup means there will have been at least 60 matches this term.
So it would be easy to forgive the squad if they were currently feeling below their physical peak ahead of Saturday’s trek to Sunderland.
But the Blues are currently on a run of seven straight league victories and Nathan Thompson believes that is keeping fatigue at bay.
The right-back said: “When you’re winning it gives you more energy and you use the momentum to keep going.
“If we’d lost twice over Easter, then it would be tougher going all the way up to Sunderland. Instead we’re full of confidence.
"This team never knows when it’s beaten and we’ll always continue to plug away to try to get positive results."
“There’s a desire to keep going and I think we’ve shown the character and fitness levels in our squad in recent weeks.
“This team never knows when it’s beaten and we’ll always continue to plug away to try to get positive results.
“The boys deserve automatic promotion this season, but we have to keep working hard and see how it all pans out.”
Pompey will secure Championship football if they win their next three games, but Sunderland are just two points behind them.
Thompson said: “It’s a huge game – I think it even eclipses the final of the Checkatrade Trophy because our aim at the start of the season was promotion.
“Everyone knows the importance of it and with the way Barnsley are going, we know we have to keep putting three points on the board.
“But we may have that psychological edge because of those two previous results against Sunderland this season.
“We’ve got ourselves into a really strong position now and it would be a crying shame if we let that slip away.”