Kevin Phillips' 50th-minute strike and a late effort from Lee Clark gave Sunderland the points and moved Peter Reid's side another step closer to a return to the Premiership.

Phillips produced a cool finish to control the ball with his chest and slot the ball past Aidan Davison following a wonderful pass from the industrious Nicky Summerbee.

And with Grimsby pressing for an equaliser, former Newcastle man Clark reacted first in a congested penalty area to steer Sunderland past the psychologically important 80-points barrier.

The points were precious for the First Division pacesetters, but they were made to fight all the way and were fortunate to turn around level.

Sunderland's debutant goalkeeper Andy Marriott finally got his opportunity in the first team 10 months after moving from Wrexham and he made the most of it.

It was the Welsh international, named in the side with regular keeper Thomas Sorensen ruled out with concussion, who saved the First Division leaders on 21 minutes when he reacted well to keep out a goalbound effort from Dave Smith.

It was the clearest chance of the half for the Mariners, who suffered a real blow to their play-off hopes with this result. Alan Buckley's side began the day four points adrift of the play-off zone, but with games in hand they fancied their chances of making a late run.

Even after going 1-0 down, Grimsby showed plenty of spirit and former West Brom midfielder Kevin Donovan, who followed Buckley to Blundell Park, came close to providing an equaliser for the Mariners.

Five minutes after Phillips' goal, Donovan broke clear and should have done better, but his ball into the danger area was gratefully cleared by the Sunderland defence.

Donovan then claimed he should have had a penalty midway through the second half when he appeared to have his shirt pulled.

For all Grimsby's best efforts, Sunderland always looked a threat on the break and visitors almost increased their lead when Tony Gallimore had to be alert to block an effort from Summerbee.

Buckley introduced Lee Nogan for Dave Smith in the final stages and the substitution did at least give the otherwise well-organised Sunderland defence something to think about.

Yet, it was Reid's men who sealed victory with a simple goal for Clark 11 minutes from time following a goalmouth scramble. Clark's goal was greeted with jubilation from the 2,200 visiting fans who chanted "We're going up."

After this hard-earned win it is hard to see anything stopping them returning to the big time.

Teams:

Grimsby: Davison, McDermott, Gallimore, Handyside, R. Smith, Widdrington, Donovan, D. Smith (Nogan 66), Ashcroft, Clare,Groves.

Subs Not Used: Burnett, Lever.

Sunderland: Marriott, Makin, Gray, Ball, Melville, Butler, Summerbee, Clark, Quinn (Dichio 80), Phillips (Bridges 80),Johnston.

Subs Not Used: McCann.

Booked: Ball.

Goals: Phillips 50, Clark 79.

Att: 9,528

Ref: E Lomas (Manchester).