It completed a satisfying double for the League leaders following their 5-1 thrashing of United last November.
Disguised somewhat by their FA Cup form, this was United's third successive League defeat and saw them drop out of the play-off places. Sheffield's next game is a week today, when West Ham will be the visitors in a fourth- round Cup replay. The winners will earn a trip to Highbury to play Arsenal.
But despite their continued excellence in cup competitions, manager Neil Warnock has found it hard to coax consistent performances out of his side in the League. Yesterday, he recalled Danny Cadamarteri in place of Andy Liddell, whose two strikes in the third round of the FA Cup helped account for Aston Villa, but who has failed to score since.
Initially it had the desired effect as Sheffield started strongly. Cadamarteri's first involvement was an ambitious attempt from the edge of the area when Andy Gray, unmarked, was screaming for a simple pass that would have given him a clear sight of goal.
Gray did receive the ball, in United's next attack, though, drawing a diving save from Kelvin Davis. From the resulting Jon Harley corner, Phil Jagielka headed over from six yards.
All this was within the first 10 minutes as Ipswich struggled to match their hosts' early intensity. Accordingly, it was entirely against the run of play when the visitors went ahead midway through the first half.
Shefki Kuqi held the ball up long enough for Unsworth to come thundering past him and be able to receive a neat ball into his path. The former Everton defender shaped to cross and, as Paddy Kenny crept across his goal to anticipate the delivery, smashed the ball into the roof of the net inside the keeper's near post.
United, to their credit, responded well, but there was a developing theme of Ipswich using their limited possession economically. A dipping drive from leading scorer Darren Bent almost caught Kenny out from one break, while Kuqi was a persistent nuisance to Sheffield's back three.
Just before the break, United wasted their best chance. Michael Tonge's free-kick cleared everyone apart from Leigh Bromby at the far post, but the defender directed his header the wrong side of the post from close range. Sheffield started the second half in the same way they had ended the first, Gray drawing another good stop from Davis within seconds of the restart.
Soon afterwards Davis was at full stretch to tip away a clever, curling effort from Tonge, by now at the heart of all his team's best moves.
Ipswich were still a threat on the break, though. When a corner was only partially cleared, Ian Westlake's shot was deflected into the path of Kuqi, eight yards out. As the Sheffield defence appealed for offside, he had plenty of time to control the ball before slipping it past Kenny.
Warnock introduced extra forwards in the form of Liddell and Ashley Ward, changing his side's formation in a bid to salvage a point.
It made no difference and a return to cup action cannot come quickly enough for the Blades.Reuse content