33-year-old Keane, whose last goal for United came last November in a 3-0 league win against Portsmouth, joins Ronaldo, O'Shea and Giggs in Sir Alex Ferguson's midfield.
European hat-trick hero Wayne Rooney links up with Ruud van Nistelrooy up front.
Man Utd: Carroll, Gary Neville, Ferdinand, Silvestre, Heinze, Ronaldo, O’Shea, Keane, Giggs, Rooney, van Nistelrooy. Subs: Ricardo, Smith, Kleberson, Djemba-Djemba, Fortune.
Middlesbrough: Schwarzer, McMahon, Riggott, Southgate, Parnaby, Morrison, Mendieta, Boateng, Downing, Zenden, Nemeth. Subs: Nash, Doriva, Cooper, Taylor, Graham.
Referee: R Styles (Hampshire)