A colossal error by the men on the United bench may have cost them the Premiership title they covet intensely.

United were a goal up, courtesy Kieran Richardson’s third-minute strike, and appeared to be handling Middlesbrough comfortably when Rio Ferdinand signalled to Sir Alex Ferguson and coach Carlos Quieroz that his groin was troubling him.

He could not run, but they left him on for fully five minutes and in that period Middlesbrough scored an unlikely equaliser (as reported in Sunday’s Late City edition). As Mark Viduka moved in front of Wes Brown to head in Stewart Downing’s left-wing cross, Ferdinand was unable to take up a position. He should have been substituted.

Ferguson confirmed that Ferdinand will be out for at least two weeks, missing Tuesday’s Champions League semi-final first leg against AC Milan. But, perhaps most damaging of all, he and everyone concerned at Old Trafford may look upon those minutes of time added-on at the end of the first half as the moments when the title was lost.

They might even have lost had referee Peter Walton given a last-minute penalty when Middlesbrough’s Korean, Dong Gook Lee, went down as John ’Shea challenged.