Neil McRoberts blamed yellow-card fever for Gosport & Fareham’s 22-16 London one south defeat at Hooks Lane.
The visitors found themselves down to 13 men midway through the first half and Havant were quick to exploit the situation.
The hosts scored two tries before half-time to put themselves in the driving seat.
McRoberts’ team chased the game in the second half but couldn’t make up the lost ground.
‘The period when we went down to 13 men killed us,’ said Gosport & Fareham’s head coach.
‘It came at a time when we were forcing ourselves into the game.
‘We were starting to get on top with our big ball carriers getting in among them.
‘It was becoming a bit of an arm wrestle which suited us but the yellow cards handed the initiative to Havant.
‘The lack of discipline cost us, although, I thought both cards were a little harsh.’
Kieran McRoberts was the first to go to the sin-bin in the 25th minute after he spoke out of turn to the referee.
He was followed five minutes later by prop forward Tom Blackburn for taking a player out in the air.
Although Wayne Dugan knocked a penalty, the visitors found themselves trailing 12-3 at the interval.
A Ben Roberts try at the start of the second half reduced the arrears but Havant quicky added a converted try and a penalty.
At the death Blackburn forced his way over close to the posts and Sam Foster converted to give Gosport a precious bonus point.
‘It was a cracking, hard-fought game of rugby which lived up to its billing,’ said Neil McRoberts.
‘Although it was disappointing to lose the game, it was a great advert for Hampshire rugby.
‘It was the first time this season we probably deserved to get a win away from home.
‘On this performance our first away win won’t be too long in coming.
‘Getting the bonus point was important because it bumped us out of the bottom three.
‘Psychologically that is important going into the second half of the season.
‘Only eight points separate the bottom six clubs, so it is becoming a bit of a dogfight at the bottom.’