Tim Cahill kept Millwall on course for the play-offs with a last-gasp winner just as it looked as though Rotherham had earned a point.

The Millers, who had been second best for most of the evening, hauled themselves level when Martin Butler was upended in the area.

Former Sunderland striker Michael Proctor converted the resulting penalty into the top corner but the drama had not finished.

Substitute Peter Sweeney swung in a cross from the left and Cahill sent a powerful header across the face of the goal and into the top corner.

Neil Harris had earlier given the Lions a first-half lead with his first goal since Boxing Day.

Harris latched on to Danny Dichio's headed flick-on, cut inside a defender and drilled the ball into the bottom corner seven minutes before the break.

Millwall made the kind of confident start you would expect from a side unbeaten in their last eight league and cup games.

Paul Ifill delivered an inch-perfect cross to the near post only for Cahill to send his header just wide.

The Millers went close to breaking the deadlock in the 10th minute when Chris Sedgwick's cross was well controlled by Martin Butler in the box, but Kevin Muscat prevented a certain goal with a crucial block.

The action was swinging from end to end as Ifill's shot from 20 yards was well saved by Mike Pollitt, while Rotherham's Shaun Barker headed Garner's corner wide.

The Yorkshiremen created the first chance of the second half as Garner's out-swinging corner was headed goalwards by Chris Swailes.

Winger Andy Monkhouse, who made a great interception to prevent Dichio from scoring in the first half, pressed forward with a great run, but he was dispossessed by defender Darren Ward.

Wise responded for Millwall with a strike from 25 yards which was easily kept out by Pollitt, but again Rotherham pushed forward in search of an equaliser.

Butler had a shot blocked by Ward and moments later Sedgwick could not find the target from close range.

Sedgwick had Rotherham's best chance of the match in the 65th minute when he managed to steer Paul Hurst's cross over the bar from inside the six-yard area.

But the visitors started to run out of gas as Cahill forced Pollitt into action with a header which was followed by a 25-yard effort.

Sweeney, on for the injured Ifill, cleared the crossbar with a rising drive and Dichio missed with an overhead kick and then headed over before the Lions claimed victory in a thrilling finale.

Teams

Millwall Gueret, Muscat, Lawrence, Ward, Ryan (Elliott 70), Ifill (Sweeney 70), Wise, Cahill, Livermore, Harris, Dichio.

Subs Not Used: Marshall, Roberts, Braniff.

Goals: Harris 38, Cahill 90.

Rotherham Pollitt, Stockdale, Swailes, Shaun Barker, Hurst, Sedgwick (Richard Barker 87), Garner (Warne 76), Mullin, Monkhouse (Baudet 76), Proctor, Butler.

Subs Not Used: Montgomery, Minto.

Booked: Garner, Monkhouse.

Goals: Proctor 90 pen.

Att: 8,254

Ref: P Walton (Northamptonshire).