Millwall had assistant Adam Barrett taking charge for the afternoon, following manager Gary Rowett's positive coronavirus test, and they were just unable to make it three wins in a row.

Barnsley were forced into making two late changes before kick-off after Jordan Williams and Cauley Woodrow were injured in the warm-up, with Clarke Oduor and Conor Chaplin taking their places.

The Tykes can be forgiven for being slow to start after that disruption, but Millwall themselves were under a malaise during an opening quarter that saw neither team have so much as a half-chance.

Barnsley goalkeeper Jack Walton almost injected some excitement into what had been a dire first period when he came racing out of his area but, fortunately for him, he just about beat Jed Wallace to a loose ball.

Completely out of the blue, Mowatt lashed the visitors in front after 44 minutes when he arrowed a stunning shot into the top corner from 25 yards after a cross was headed out into his path.

The Tykes couldn't hold their lead until half-time, however, as Connor Mahoney's corner found Cooper at the back post and Walton was unable to keep out his header.

Walton had to have his wits about him, though, as he had to be on hand to turn Jed Wallace's free-kick from out on the left over the bar in the early stages of the second half.

Millwall almost completed the turnaround after 58 minutes when Mahlon Romeo's superb cross found Mason Bennett and Walton did superbly to tip his effort onto the post.

The Lions were then frustrated by the woodwork for a second time when Scott Malone's looping header from Bennett's cross came back off the bar.

Bartosz Bialkowski had little to do in the Millwall goal, but he left nothing to chance in keeping out a free-kick from Herbie Kane which looked to be sneaking into the top corner.

Walton then came to Barnsley's rescue again in the 90th minute when he produced a superb save to keep out Kenneth Zohore's header.