Rob Matthews insists Havant have to rid themselves of their mid-table mindset between now and the end of the season.
The Hooks Lane outfit need to improve if they are to get back to winning ways against visitors Sutton & Epsom in London one south.
Matthews was disappointed with the defeat at Twickenham – where his side came up against a team that showed more hunger and desire.
‘Twickenham are fighting for their lives at the lower end of the league,’ said Havant’s director of rugby.
‘We are in a comfortable position in mid-table and that showed.
‘It is vital we get out of that mindset and show we can compete against the top teams.
‘Sutton & Epsom will give us the opportunity to do just that.
‘We have a massive cup final against Gosport & Fareham at the end of the season and we need to make sure we go into that in the right frame of mind.’
Havant are boosted by the return of a number of influential players, including Steve Cruddas at hooker.
Mike Brook, Jo Davis and Jared Hayler will provide them with a balanced back-row.
Grant Morris impressed at Twickenham when he went on as a replacement scrum-half and as a result gets the start.
Winger Josh Blackburn is also in the replacements for the first time this season after returning from Army duties.
Ben Brierley and the injured Darren Bamford are both missing, though.
Portsmouth visit Warlingham seeking points in their fight to avoid London two south west relegation.
Head coach Ian Chandler admits time is running out for his team, who are one place above the drop-zone.
‘If the league finished today then we would stay up,’ he said.
‘But we can’t assume the two teams below us won’t win any games and have to win to keep it in our own hands.
‘The rest of our games are against teams in and around us, so it is up to us to do the business.’
In Hampshire two, Southsea Nomads host Fawley at Furze Lane having notched their first success of the season at Kingsclere last weekend.