Millwall versus Sheffield United: Kyron Gordon the only positive on a miserable day at The Den

But what really troubled Paul Heckingbottom, who has repeatedly warned the road towards Championship play-off qualification is littered with potholes, was the manner in which his team not only surrendered its nine match unbeaten run but also sixth place in the table.

Insipid, ineffective and lacking the drive which has become their trademark since Heckingbottom’s appointment three months ago - although Gary Rowett’s men were little better for long periods of this forgettable contest - United looked anything but a side in the thick of a promotion battle.

Perhaps it was fatigue, following a gruelling run of games which has exposed the folly of only recruiting one new face during the winter transfer window. Or, as Heckingbottom suggested afterwards, a lack of focus.

Either way, a repeat performance when fellow contenders Nottingham Forest travel to South Yorkshire on Friday could have serious consequences for United’s hopes of reaching the top-flight next term.

“It’s a reminder,” said Heckingbottom, who was nevertheless pleased with Kyron Gordon’s contribution on his league debut. “There’s ways to get beat and, for me, that was about us not being at our best.”

Gordon’s inclusion was a sign that, rather than paying lip service to promoting from within, Heckingbottom really does view United’s development programme as a source of fresh talent. But with Charlie Goode suspended, Chris Basham injured and Ben Davies better suited to operating on the other flank, the youngster’s presence in the starting eleven for such an important fixture also served to remind how painfully thin Heckingbottom’s squad has become following a spate of fitness issues.

Initially tasked with marshalling the in-form Mason Bennett, until the former United target hobbled out of the contest, Gordon acquitted himself well; demanding possession, even if he didn’t always get it, and barking instructions to those around him.

But stiffer tests will come, with neither Millwall nor United showing any great ingenuity going forward during a soporific first-half.

Whether or not the inaction was born out of mutual respect or a sign the schedule is beginning to take its toll, only Heckingbottom and Rowett will truly know. But the fact both teams began the second period with more purpose suggested that, whatever the reason, neither had tempered their criticism during the interval.

Typically, given the dearth of quality before the break, the first genuine chance of the afternoon came via a mistake; United’s Wes Foderingham spilling a low shot from Shaun Hutchinson before George Saville went close on the rebound.

Earlier, Jack Robinson had nearly caught out Bartosz Bialkowski when he sent a long range effort towards the top of the Millwall net only to see it turned behind for a corner.

But it wasn’t until the 61st minute that something of note happened. And unfortunately for United, the thing that broke the boredom was a goal for the hosts - Cooper climbing above everyone else to meet a Jed Wallace free-kick and divert the ball home. The centre-half was also on target when Millwall triumphed at Bramall Lane earlier this term.

“Coops certainly enjoys playing against Sheffield United,” Rowett acknowledged. “He’s always a danger.”

Millwall: Bialkowski, McNamara, Wallace, Hutchinson (Ballard 64), Cooper, Wallace, Malone, Saville, Bennett (Evans 16), Mitchell, Burey (Lovelace 90). Not used: Long, Pearce, Mahoney, Afobe, Lovelace.

Sheffield United: Foderingham, Baldock, Norrington-Davies, Gordon (Berge 71), Egan, Robinson, Norwood, Hourihane (Fleck 87), Ndiaye (Gbbs-White 56), McBurnie, Sharp. Not used: A Davies, B Davies, Jebbison, Starbuck.

Referee: M Salisbury (Lancashire).