Sheffield United left baffled about key man's injury ahead of big Middlesbrough trip

Osborn had been introduced as a half-time substitute for John Fleck, who was rested with Sunday’s trip to Middlesbrough in mind, before making way himself later in the half after receiving treatment from the Blades’ medical staff at The Hawthorns.

Osborn first reported an issue with his hamstring after United’s victory over Millwall last weekend, but a scan reported no damage and he trained with no issues on the eve of the cup game in the Midlands, which United went on to lose 1-0.

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“Ozzy can still feel his hamstring,” Heckingbottom confirmed. “The scan showed no damage and the [medical] guys are thinking it might be a bit neural and coming from somewhere else.

“He trained fine before the game, did the warm up and a few sprints but then he became aware of it in the game and it started to restrict him a little bit.

“So we didn’t want to take any chances. The initial scan didn’t report anything so we’ll have to look into it. But we’re not sure at the minute.”

The United chief, who made five changes for the cup tie, confirmed that Fleck’s half-time substitution was pre-planned.

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“If we had more boys fit, we’d have made more changes tonight,” Heckingbottom, who has Oli McBurnie, Chris Basham, Jack Robinson and Jayden Bogle still sidelined, added.

“But we didn’t, so we had a couple of changes in our heads, to make sure we kept some energy in the legs for the team we’ll possibly pick on Sunday.”

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