National League leaders Wrexham were denied another FA Cup giant-killing as a stoppage-time equaliser from Republic of Ireland defender John Egan ensured 10-man Championship high-flyers Sheffield United forced a replay after an absorbing 3-3 draw.The famous old Racecourse ground has witnessed its fair share of shocks - with a picture of Mickey Thomas' famous free-kick goal against Arsenal in the FA Cup in 1992 hanging on the wall of the Turf Hotel adjoining the stadium - and this was almost one for a new era at the club.Watched by one half of their Hollywood ownership duo in Ryan Reynolds, Paul Mullin's 27th goal of the season four minutes from time looked like giving them a victory which was no more than they deserved after going behind after just 64 seconds.Blades striker Daniel Jebbison's senseless sending-off with 20 minutes to go undoubtedly helped their cause, although they were already in the ascendency before then, and they duly capitalised.But just as they were contemplating a place in the fifth round, Egan popped up with an equaliser to take the tie back to Bramall Lane.It was a cruel blow for the side 70 places below their visitors, second in the Championship, but the performance was a ringing endorsement of the huge steps being made under the leadership of Reynolds and fellow actor Rob McElhenney.In only the second minute Oli McBurnie slipped his marker Jordan Tunnicliffe to head Tommy Doyle's corner past Luke Young guarding the near post.In a further blow for the hosts, Tunnicliffe was forced off after getting injured trying to stop the striker and, by the 10th minute, Wrexham had been forced into another change with the second member of their back five, Aaron Hayden, also departing with a calf problem.Mark