Ian Chandler believes greater mental strength is needed if Portsmouth are to retain their London two south west status.
The club remain in big trouble following their 36-16 derby defeat to Winchester at Rugby Camp.
Chandler, hit by a number of late call-offs due to a flu bug and a stag weekend, was forced to call up players on Saturday morning.
‘If we are going to avoid relegation, greater commitment is needed,’ said the head coach.
‘The players have said they will now be available for the rest of the season. By my reckoning we need to win half of our remaining six games to stay up and two may even be enough.
‘I know we have the ability in our squad to achieve that but have to ask whether we possess the mental strength.
‘Our fate is in our own hands.
‘We just have to show we are good enough to stay up.’
Playing against the wind, Portsmouth trailed 19-9 at the break with Simon Morgan kicking two penalties.
It looked promising when 18-year-old winger Ed Hopkins scored his maiden try for the first team two minutes into the second half.
Morgan’s conversion brought the score back to 19-16 but it proved to be false hope for the hosts.
When Chris Morgan was yellow-carded for failing to roll away after a tackle, Winchester quickly scored two tries to leave Chandler’s team chasing the game.
Hampshire one leaders United Services came through their sternest test yet to win 32-27 at Millbrook.
The unbeaten visitors have opened up a 10-point gap at the top and remain favourites for the title.
‘It was brutal,’ said Services director of rugby Matt Davis.
‘Millbrook are a good side with a good pack of forwards and strong running backs.
‘It was easily our toughest game of the season and we had to be at our best, particularly in the closing stages when they threw the kitchen sink at us.’
Steve Gee and Luke Peters were among the try scorers.
Fareham Heathens slipped to a 25-22 defeat against Fordingbridge at Cams Alders.
Petersfield thumped Romsey 64-7 at Penns Place.