Grimsby suffered defeat on their return to the Football League as Leyton Orient eased to a 2-0 win at Brisbane Road.
The Mariners, promoted back at the end of last season via the National League play-offs, were beaten by a penalty from George Moncur and wonder strike from Tom James.
The second half was just three minutes old when the O’s broke the deadlock.
Referee Chris Pollard adjudged Luke Waterfall to have handled a Moncur shot and debutant Moncur calmly sent his spot-kick low into the corner of the net.
A stunning strike doubled the lead in the 56th minute. James collected the ball following a corner and unleashed a venomous 30-yard drive into the net off the underside of the crossbar.
Orient were never threatened after that, although the visitors had caused some moments of concern before the break with efforts from Michee Efete and Gavan Holohan bringing reaction saves from Lawrence Vigouroux.
