The Mariners eased to victory in the first fixture in Devon at Bideford AFC tonight. Goals by Mitch Rose (2), Scott Vernon and Adi Yussuf sealed the win.
Town boss Russell Slade included three unnamed trialists in tonight’s side.
The visitors were quick out of the blocks and soon had Bideford under pressure.
Dembele and Kelly combined well down the left before the latter’s volley drifted just wide.
But minutes later Town were ahead. After a mix-up in the Bideford defence, Mitch Rose nipped in to stab the ball home.
On 21 minutes Town almost doubled the lead when Berrett’s low free-kick went inches wide.
Dembele saw his effort turned around the post by the Bideford keeper, before Scott Vernon's neat flick came back off the post.
On 44 minutes Town deservedly doubled their lead, as Rose broke through the home defence and smashed the ball home.
Half-Time: Bideford AFC 0-1 Grimsby Town
Almost straight after the interval the Mariners were three ahead, this time it was Scott Vernon's turn to get onto the score-sheet, tapping home at the far post.
And Vernon almost got his second soon after. Town hit the hosts on the break, but this time the big striker's cross-shot went just wide.
It was all change on the hour as Russell Slade sent on Adi Yussuf, Harry Cardwell, Luke Summerfield, Tom Bolarinwa, Jamie Osborne, Ben Davies, Jack Keeble and two trialists - replacing Scott Vernon, Sam Jones, Siriki Dembele, Nathan Clarke, Danny Collins, trialist, Zak Mills, Sam Kelly, and James Berrett.
On 65 minutes Town looked to have gone further ahead but one of the trialist's shot rebounded off the post and fell kindly into the keeper's hands.
But the fourth was soon to come - as Adi Yussuf out-paced the Bideford defence and slotted the ball under the keeper.
On 74 minutes Bideford almost pulled one back, but Smallcombe's strike bounced off the post and was cleared.
Good play down the left by Summerfield and a whipped cross, found the head of Osborne, but his effort was fielded well by the home side's stopper.
Full -Time: Bideford AFC 0-4 Grimsby Town
Town Starting Xl: McKeown, Mills, trialist, Berrett, Clarke (c), Collins, Dembele, Rose, Vernon, Jones, Kelly.
Subs Keeble, Osborne, Killip, Cardwell, trialist, trialist, Davies, Bolarinwa, Summerfield, Yussuf.