There was a warning for the visitors in the third minute when Gavin Cowan headed just over after a corner kick from the left, but Frickley responded four minutes later, Ryan Mallon picking out Brad Grayson, who cut in from the right and put a strong shot into the side netting from a tight angle.
Grant Darley whipped in a cross from the left in the 11th minute and James Ashmore drilled a first time 25 yard drive inches wide of the target, while Ashmore provided an accurate free-kick four minutes later and Lincoln Adams linked up with the attack to go close at the far post.
Gainsborough were stung into action, and it needed a reflex save from Adam Billard
to turn a point blank header from Cowan over the bar in the 17th minute, while Ryan Kendall ran unmarked to meet a free-kick from the right, but lifted his effort over the top.
The Evo-Stik Premier side were giving as good as they got and when an effort from Ashmore was only half cleared in the 28th minute, Darley drilled a 20 yard shot just off target, while Leon Henry
pounced on a some confusion caused by a cross from the right by Mallon but saw his overhead kick clear the crossbar eight minutes later.
Trinity thought they had broken the deadlock in the 38th minute when a cross from the right was flicked on by Darren Stamp to Kendall, who was only foiled by a fingertip save from Billard at the expense of a corner.
On the stroke of half-time, Adams beat the visiting defence to a free-kick, only to see his effort go wide, and play switched to the other end, Stamp meeting a deep free-kick but directing his header off target.
The tempo continued after the interval, Henry beating two men on the edge of the penalty area in the 49th minute, but seeng his cross to Grayson cut out, while Trinity countered and Ryan Williams shaved the bar with a 20 yard drive.
The deadlock was broken in the 55th minute when a deep cross from the left was met with a looping header from Stamp which dropped just inside the far post to put Gainsborough in front.
A good run by Henry two minutes later saw him pick out the overlapping Kelvin Bleau, only for him to lift a strong 20 yard shot over the top.
Trinity struck again in the 65th minute when a misunderstanding between Adams and Billard allowed Kendall to nip in and find the net.
Kendall should have scored again five minutes later when he turned Stuart Ludlam
but lashed his effort wide, and sub Lewis McMahon was denied by another fine save from Billard in the 73rd minute.
Although manager Peter Rinkcavage brought on Ollie Ryan and Jack Watts
for Grayson and Darley in the 77th minute, they were unable to make much headway and Gainsborough continued to look threatening going forwards.
Gainsborough: Andy Pettinger, Dominic Roma (Michael Leary 59min), Kevin Sandwith, Gavin Cowan, Andy Boyce, Craig Nelthorpe, Jonathan D'Laryea, Ryan Williams, Ryan Kendall, Darren Stamp (Ryan Paczkowski 83min), Jamie Yates (Lewis McMahon 63min); unused subs, Luke Waterfall, Rory Coleman, Mark Gray
, Jonathan Williams.
Frickley: Adam Billard
, Kelvin Bleau, David Cyrus, Danny Walsh, Lincoln Adams, Stuart Ludlam
, Ryan Mallon, James Ashmore, Brad Grayson (Jack Watts
77min), Grant Darley (Ollie Ryan 77min), Leon Henry
87min); unused Michael Simpkins
, Ben Saynor
, Karl Jones
Referee : Mr. C. Kavanagh