The rival Yorkshire managers have patched up a relationship that turned acrimonious after a bust-up at Bramall Lane seven years ago. But Blackwell inflicted agony on Ternent again last night in the second round of the Carling Cup.

With eight minutes to go, Town looked to be heading into the third round for the first time in five years thanks to a first-half goal by Michael Flynn.

But two goals in two minutes by striker Darius Henderson and substitute Kyle Naughton got the Blades off the hook.

Ternent had suffered an earlier blow when his bid to strengthen Town's attacking options with the capture of Dagenham and Redbridge winger Dominic Green had been hijacked by Peterborough United.

Town agreed a fee for the 19-year-old but were unable to persuade the player to move north to Yorkshire.

Ternent was desperate to improve things after his side's weekend defeat to Milton Keynes Dons and plainly had Carling Cup progress in mind when choosing his side.

Unable to call upon the services of Liam Dickinson and Ian Craney and without the injured Andy Butler, Ternent made only one unforced change, dropping midfielder Jim Goodwin to the bench.

Summer signing Keigan Parker made his first start for the club and there were recalls for Jon Worthington, Nathan Clarke and Luke Beckett.

Blackwell, in stark contrast, made wholesale changes – resting seven players who had started the club's weekend win at Blackpool.

Although club record signing James Beattie was still not ready to play after a knee injury, the striker warmed up with the rest of his team-mates before the game and carried on his solo training session until moments before the first whistle. He is now expected to be involved in this weekend's game against Cardiff.

The Blades had an early scare when a header from Town winger Gary Roberts struck the outside of the post.

Town kept up the pressure and went close again when defender Nathan Clarke headed wide from Chris Lucketti's cross.

Although the two managers are now the best of friends, it soon became apparent that their players were in no mood to foster harmony.

Defender Sun Jihai escaped a caution for a crude two-footed challenge on Town winger Danny Cadamarteri, but Blades striker Henderson picked up a yellow for charging into the back of Nathan Clarke.

Town eventually took the lead on 34 minutes after another foul by Sun on Cadamarteri resulted in a free-kick deep in Blades territory.

Roberts knocked the ball into the path of Flynn whose 25-yard drive flew into the net via a deflection off Matthew Spring.

In a bid to turn things round, Blades manager Blackwell sent on striker Danny Webber as a replacement for Jon Stead who had failed to sparkle on his return to the club where he started his career.

But the Blades would have gone further behind had it not been for a fine low save by goalkeeper Ian Bennett to deny the impressive Roberts.

Town continued to take the game to the visitors and former Blades striker Beckett headed wide as the Blades defence struggled to cope.

Beckett's tussle with former Barnsley team-mate Chris Morgan would prove to be one of the most physical of the evening.

Town coach Ronnie Jepson made numerous protests to the referee about the tactics employed but the pair were allowed to carry on regardless and seemed to be enjoying it.

Blackwell's decision to rest so many players had contributed to his side's subdued display. There was still enough quality on the field, however, to have produced a far better overall performance.

However, just when things looked to be slipping away from the Blades, the game was turned on its head and Town conceded two goals in as many minutes.

Henderson, a £2m summer signing from Watford, drove in his first goal for the club quickly followed by Naughton's first in senior football.

Despite the result, Town will aim to maintain last night's performance level in Saturday's trip to Millwall where a first league win of the season will be the target. The Blades will entertain Cardiff buoyed by this lucky escape.

Huddersfield Town: Glennon; Holdsworth, Lucketti, N.Clarke, Williams (Kamara 88); Cadamarteri, Worthington (Jevons 85), Flynn, Roberts; Parker, Beckett (Goodwin 77). Unused substitutes: Skarz, Collins, Unsworth, Smithies.

Sheffield United: Bennett; Geary (Sharp 86), Morgan, Kilgallon, Jihai; Cotterill, Tonge, Spring, Carney (Naughton 69); Henderson, Stead (Webber 45). Unused substitutes: Kenny, Montgomery, Robertson, Ehiogu.

Referee: NS Miller (County Durham).