Oli McBurnie then sliced a shot off target from just outside the area.

Town began to threaten after the early exchanges, Harry Cornick sending over an excellent cross from the right that Elijah Adebayo could only direct into the stands.

And Cornick's long throw bounced off the head of McBurnie and into the grateful gloves of Wes Foderingham.

A bright start to the second period saw Luton threaten an opener.

Captain Kal Naismith sent in a driven cross that was too strong for Adebayo and then met Gabe Osho's hanging cross himself, only to try and set up a team-mate rather than go for goal, Allan Campbell finding the side-netting.

Fred Onyedinma thought he had put Luton in front after 56 minutes, taking Naismith's long ball in his path and going through to poke past Foderingham, but he was adjudged offside and the goal was disallowed.

Adebayo then closed down Foderingham, whose clearance went only as far as Cornick. He beat his man but, from eight yards out, crashed a shot against the underside of the bar.

Naismith's long-range effort was well handled by the Blades goalkeeper, but at the other end all United could muster was a weak Luke Freeman effort that dribbled through to Simon Sluga.

Onyedinma had another go on his left foot, powering a shot into the side-netting, with the winger also denied by the legs of Foderingham from Adebyao's slipped pass.

Town went close again with three minutes left as James Bree let fly from 20 yards, but the effort curled just the wrong side of a post.

In stoppage time, Blades midfielder Sander Berge went down in the area under a challenge from Pelly-Ruddock Mpanzu, but referee Andy Davies waved away the penalty appeals as both sides had to make do with a point.