Leyton Orient began the 2022-23 League Two season in winning style at Brisbane Road.
George Moncur's penalty gave Richie Wellens' side the lead early in the second half, with Tom James adding a stunning second soon after.
And it was no more than the hosts deserved, having enjoyed the better of proceedings on the first day of the new campaign.
After both sides had observed a minutes applause for O's fan and journalist Rowland Lyons, who had been tragically killed in a road accident in Somerset at the start of the week, the home side had their first chance on four minutes when Theo Archibald found Moncur, whose bending effort was palmed away by Max Crocombe.
O's went close four minutes later when Moncur beat his man and found Ruel Sotiriou, who flashed a shot wide of the post, but Lawrence Vigouroux was called upon on 11 minutes to deny Michee Efete at the far post with a superb save.
Crocombe thwarted Paul Smyth moments later, with Sotiriou curling a shot wide in a lively opening quarter of an hour.
And Smyth then drilled another shot just past the far post having collected a chipped pass from Archibald on 18 minutes.
A clash of heads between two Grimsby players led to a brief delay, but O's were inches away from taking the lead on 34 minutes when Moncur fired a free-kick just wide.
Vigouroux got down to make a comfortable save from John McAtee four minutes before the break, with James booked for a foul on Bryn Morris during stoppage time and new signing Rob Hunt also shown a yellow card before the interval.
O's had a let-off within two minutes of the restart as Morris shot wide from 12 yards but the hosts were then awarded a penalty seconds later when Moncur's shot was handled by a Grimsby player in the box.
And Moncur stepped up to drive the spot-kick into the bottom right corner of the net to break the deadlock.
O's maintained a high tempo to their play in search of a quick second and they got it on 56 minutes as James netted with an emphatic 30-yard strike in off the crossbar for an early goal of the season contender.
Hunt made way for Craig Clay just before the hour, with James moving back to left-back, as the home fans began to create a party atmosphere in E10.
And the two goalscorers combined on 62 minutes with James pulling the ball back for Moncur to fire over the crossbar, while Archibald's dummy free-kick was almost sliced into his own net by Harry Clifton six minutes later.
Sotiriou shot just wide from the corner and Smyth made way for Harry Smith with a quarter of an hour remaining, while Grimsby's Ryan Taylor was booked for blocking a Vigouroux clearance.
Jayden Sweeney replaced Sotiriou in the closing stages, with Omar Beckles shown a yellow card for a trip on McAtee four minutes from time.
And Archibald and Moncur almost combined for a third O's goal in the last minute of normal time, but Crocombe was able to smother the pass just in time.
The visiting keeper produced a good save to touch Archibald's shot past the post in the first of five minutes of stoppage time as O's had to settle for just the two goals on this occasion.
Leyton Orient: Vigouroux, James, Happe, Thompson, Smyth (Smith 75), Sotiriou (Sweeney 80), Archibald, Moncur, Pratley, Beckles, Hunt (Clay 58). Unused subs: Sargeant, Georgiou, Fish, Obiero.
Attendance: 8,557.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here