FA Cup | Mon, 19 Mar 07, 20:00 | Old Trafford
Belfast-born teenager Craig Catchcart has been called into an injury-hit Manchester United squad.
Wes Brown will replace Gary Neville (ankle), Alan Smith may take over Ryan Giggs' striking responsibilities.
Middlesbrough hope the knee injury which saw Emanuel Pogatetz stretchered off against Manchester City is not as bad as first feared.
Jonathan Woodgate and Mark Viduka return after being rested against City, Julio Arca (groin) is doubtful.
Man Utd: (from) Kuszczak, Heaton, Brown, Ferdinand, Vidic, Cathcart, Heinze, Evra, Park, Carrick, O'Shea, Ronaldo, Giggs, Richardson, Smith, Rooney, Dong.
Middlesbrough: (from) Schwarzer, Jones, Parnaby, Davies, Xavier, Woodgate, Pogatetz, Riggott, Taylor, Boateng, Cattermole, Arca, Downing, Morrison, Euell, Johnson, Rochemback, Viduka, Yakubu, Lee.
Winners: face Watford in the semi-finals on 14 or 15 April.