Rigg's last league goal was at Havant
in mid-October but he couldn't replicate his winner at Westleigh Park.
This stalemate saw the Heed drop out of a play-off position, while Havant
are now just one point above the relegation trapdoor.
Steven Rigg's 56th-minute header saw the Heed win 1-0 on their first visit to Havant
, meanwhile, have had a mixed start since coming up as champions of National League South at the end of last season and have gone five games with a win meaning they sit 21st in the table with 11 points so far.
It had looked as though Tim Flowers' side would have to settle for a share of the points at Havant
& Waterlooville until a long throw into the box found Danny Wright and although his shot was tipped on to the woodwork by keeper Ben Dudzinski, substitute Yussuf tucked away the rebound.
The Wales international had offers to stay in the pro ranks, but the midfielder was persuaded to sign for Havant
by manager and close friend Lee Bradbury.
Bet365 have priced up Havant
as 4-6 favourites but the value lies with 3-1 shots Wood, who have won two of their last three games.
Whitchurch were finding it difficult to get into their rhythm against a quick-moving and skilful Havant
attack and goalkeeper Iwan Williams had to pull off three first-class saves to prevent his side falling further behind.
In what looks a wide open race, Havant
strikes as being full of limitless potential at this lofty grade.
The early play was largely in Lions' half with the heavy Havant
pack proving difficult to halt.
Terra Firma have worked with architects HGP and tourism consultants Planning Solutions on behalf of Havant
Borough Council to create the Masterplan, intended to give an idea of the huge potential for growth and development on the seafront.
Mike Brown, from Small World Services at Havant
lorry park, Hants, said: "Diesel is like gold dust."