The Shrimps had taken one point from nine going into the match but climbed to fourth in the League Two table with a 4-1 victory.
Cole Stockton, Carlos Mendes Gomes, Sam Lavelle and Yann Songo’o scored the goals but O’Sullivan was the star performer on the night with three assists in an all-action display.
He said: “We’re absolutely delighted with the performance, especially after the last couple of disappointing results.
“We wanted to bounce back. I think we went back to basics and showed how hard-working we are.
“From minute one, we were at it. We pressed high, we dealt with their forwards and scored some great goals.
“We needed to get back to winning ways and it showed what we’re about. We’re a hard-working side with quality going forward.
“I’m delighted with my own performance but it’s a team effort, I don’t care who scores or assists as long as we win.”
Victory leaves them four points off the final automatic promotion spot, occupied by Bolton Wanderers who visit Morecambe a week on Saturday.
They have a six-point cushion to Exeter City who sit eighth, two points adrift of the final play-off place but with a game in hand on the Shrimps.
The aim now is to try and churn out the points in the five remaining games and see where that leaves them on May 8.
O’Sullivan said: “It’s all in our hands more or less, we just keep going.
“I think everyone thinks we’re going to fade away, then we’ve come out and won 4-1 and shown what a good side we are.
“We have that togetherness, we work hard and we’ll see where it takes us. That won’t change until the end of the season.”
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