The goal signalled the start of an all-out attack by Bream Bay and they narrowed the gap again, to 3-2, with 10 minutes to play.
Mangapai needed a touch of luck when Bream Bay had a goal disallowed, finally giving them the chance to celebrate their first win in nine outings.
"The difference was that we got a few of our stars back this week and their experience helped us get through that second half," Shepherd said.
Tama Jones was outstanding at the back when Bream Bay threw everything at them and Nick Bean and Mack Bowmar also made welcome returns to the side.
Flushed with success, Shepherd now is hopeful they can continue rebuilding the team in time to perhaps craft a run at the finals later in the season.
"This season is all about the young fellows and it's good to see guys like Aden Hawker, Matt Jacobson and Chance finding their feet at this level and that's got to be good for the club's future," he said.
The other Northland men's premier match saw Maungakaramea and league leaders Springfield play out a scoreless draw.
Maungakaramea co-coach Sam Webb was frustrated with the final result after they failed to put away a few clear chances to score during the closing stages of the game.
"We're a bit disappointed but it is still early days yet, we're certainly getting better as we go along and a draw's not the end of the world," he said.
In the women's premier competition, Springfield drew level on points at the top of the table with rivals Old Girls after an emphatic 5-0 win over Maungakaramea.
Old Girls could only draw 1-1 with Hikurangi, while Whangarei Girls' High School continued their winning ways with a 6-0 win over Kamo High School.