Plymouth’s fight against relegation will go down to the final day of the Championship season after Jake Cooper’s late goal gave Millwall to a 1-0 win at The Den.

An uninspiring opening 45 minutes ended 0-0, but Cooper’s header in the closing stages won it for the hosts.

The result leaves The Pilgrims in 21st, one point clear of Birmingham in 22nd ahead of their season-defining clash against Hull at Home Park next weekend.

Having guaranteed their place in the Championship with a 1-0 win over Sunderland last weekend, Millwall looked the more confident of the two sides in the early stages.

Ryan Longman has been key to the Lions’ resurgence under Neil Harris, and the Hull loanee would have given his side an early lead were it not for Argyle goalkeeper Michael Cooper, who tipped his cross-turned-shot over the bar.

Pilgrims forward Mustapha Bundu burst into the box as the visitors looked to carve out their first chance of the match in the 22nd minute.

He almost put his side ahead, cutting through Millwall’s defence like a knife through butter before firing a blistering shot directly into the face of Lions goalkeeper Matija Sarkic.

Ryan Leonard got on the end of a superb break from a Plymouth corner 10 minutes later, but his attempt from the edge of the box was straight at Cooper.

Millwall hearts were in mouths when Plymouth’s top-scorer Morgan Whittaker went through on goal with three minutes remaining of the half, but Leonard got back to win the ball and clear it away to safety.

Duncan Watmore thought he had been put through on goal within 60 seconds of the restart only to be flagged offside.

Then Tom Bradshaw dribbled to the edge of the visitor’s box, but he could not get his shot away quickly enough to trouble Cooper.

Leonard found Watmore in the centre of the penalty area shortly after, but the winger’s glancing header was wide of the right post.

Just as The Den threatened to come unglued, Whittaker went through on goal again, but Leonard was there to put in another incredible sliding challenge and keep the scores level.

Down the other end, Longman almost set up Bradshaw at the far post with a driven cut-back across goal, but Cooper responded quickly to intercept the ball.

Watmore fired a volley just over the crossbar in the 67th minute after Casper De Norre did well to pick him out at the near post.

Plymouth were still pushing for a winner of their own though, with Lewis Gibson seeing his goal-bound shot blocked by Japhet Tanganga as the game drew to a close.

However, it was not to be, and in the 83rd minute Millwall captain Cooper produced a sublime looping header to beat Cooper and secure Millwall’s fourth win in a row.