Promotion chasers Burnley were beaten for the first time since August as Jake Cooper's headed goal gave Millwall a big win at The Den.

The Lions moved up to seventh in the Championship table and within two points of the play-off places with their third 1-0 win in a row.

Cooper's looping header in the 52nd minute proved decisive after Macaulay Langstaff and Femi Azeez had missed chances in a strong end to the opening period.

Burnley could not find a response despite having more than 60% possession and stay fourth in the table, six points behind league leaders Sunderland.

For the second week in a row, Millwall had less of the ball but proved clinical in their finishing to walk off with three points - having beaten Swansea 1-0 last Saturday.

This could be their biggest win yet. Millwall's fine form has taken them from 20th to seventh in the league in the space of 15 days.

Boss Neil Harris had bemoaned his side's defensive lapses in early matches but they have built a solidity in recent weeks and Ryan Leonard, Joe Bryan and Japhet Tanganga looked assured under the leadership of Cooper as the home side completed their third shut-out in three games.

The goal came from a Leonard long throw, initially cleared but recycled by Millwall for Azeez to send in the cross, with captain Cooper leaping high to head into the corner.

The visitors struggled to deal with the towering centre-back all afternoon and twice he was calling for a penalty kick as he went down in tussles with Clarets defender Connor Roberts.

Last week, Burnley failed to break down a dogged London team's defence, having drawn 0-0 with Queens Park Rangers at Turf Moor.

This was a similar story. And worryingly for Scott Parker, his side have now failed to score in three of their past five league matches.

Burnley started the game brightly, with Luca Koleosho and Andreas Hountondji looking particularly threatening but without troubling Millwall keeper Lukas Jensen.

A long stoppage for an injury to assistant referee Matthew Smith seemed to stunt their momentum and it was the hosts who finished the first half well, with Langstaff forcing a stunning diving save from James Trafford and the brilliant Azeez volleying over the bar.

Burnley pushed for the equaliser with long periods of possession in the Millwall half but without managing to create chances of note.

Substitute Jay Rodriguez headed over late on for the visitors but Burnley were unable to come up with the goal that would continue an unbeaten run that had stretched back to their Carabao Cup defeat by Wolves on Wednesday, 28 August.

Millwall head coach Neil Harris said:

"We're disappointed we're not higher up the league. We should have a lot more points than we have.

"We won't bemoan that because we feel we are a team going in the right direction, but we haven't come across a team better than us yet.

"The players are flying at the moment."

Burnley head coach Scott Parker said:

"The long pause in the game [when the linesman was injured] may have been a factor.

"We are a young team, the players have maybe not seen that before.

"After that point, Millwall seemed to get some momentum. Then in the second half we never really got going."