But the way Rafa Benitez's men started this game did not suggest they would suffer any sort of shock result against Simon Davey's side, who are in the bottom half of the Championship.
The home side had all the early possession and Peter Crouch forced an early save out of Steele after Yossi Benayoun had teed him up in the area.
Steele, only signed on an emergency loan from West Brom on Thursday because Barnsley's other keepers were injured or ineligible, was fast becoming a thorn in Liverpool's side.
He made two more stops in quick succession, saving acrobatically from Xabi Alonso and collecting Babel's low shot.
The former Manchester United goalkeeper was finally beaten on 32 minutes when Babel pulled the ball back for Kuyt, who took a touch before burying his shot into the back of the net.
But Steele also did brilliantly to keep out a Crouch header on the stroke of half-time and Barnsley capitalised when they equalised out of nowhere after the interval.
Devaney produced the cross of his life from out wide on the right and Foster rose highest to nod the ball past the flailing figure of Charles Itandje, who could only help it into the net.
Barnsley goalkeeper Luke Steele was making his Tykes debut
The Barnsley defence was soon back under pressure with Bobby Hassell and Foster clearing a Benayoun shot off the line before Howard's block kept out Crouch's follow-up.
And Liverpool threw everything at the visitors, forcing Steele into another smart stop from Benayoun before he tipped a Lucas header on to the bar.
There was drama at the other end too when Itandje somehow escaped without being penalised after colliding with Kayode Odejayi as he chased down a long ball on the edge of the Liverpool penalty area.
But Liverpool were still looking like the only winners and the visitors were defending desperately when Kewell saw his rasping shot hit the bar late on.
There was still time for one last Barnsley attack, however, and Howard made it count.
The Tykes captain felt he should have had a penalty after being caught by Sami Hypia but picked himself up to collect the ball on the edge of the area before firing into the bottom corner to clinch a famous victory.
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