Grimsby Town inflicted Leyton Orient's first away defeat of the season and their first reverse since the opening match of the campaign.
In the end it looked a comfortable victory for Grimsby after three straight defeats but the scoreline belied the drama of the closing stages, Leading 1-0 through Jason Crowe's 56th minute header from a free-kick, Grimsby were being pushed back as Orient pressed hard for the equaliser.
And just as the fourth official held up the board to show there were three minutes left to play the turning point occurred.
Grimsby keeper Anthony Williams made a superb save from Andy Scott's header and when the ball was quickly switched upfield Grimsby had men to spare.
Striker Michael Reddy was brought down in the box for clear penalty and midfielder Thomas Pinault, who made the first goal, dispatched the clinching second goal.
After a disappointing first half the game finally sparked into life with Grimsby's first goal and for the first time Leyton Orient showed the form that had taken them into third place.
After a poor performance at Macclesfield last week Mariners boss Russell Slade rang the changes and brought in former QPR defender Terrell Forbes for his debut.
He gave an accomplished display at the heart of the defence and with Reddy and Ashley Sestanovich also returning, Grimsby carried more threat upfront.
But after a bright start Grimsby fizzled out and it was a dreary affair until Crowe grabbed the opener, remarkably after not scoring for Grimsby at all last season.