Of United's other current injury problems, Ferguson said both skipper Gary Neville and veteran front-man Ole Gunnar Solskjaer should be back in training ahead of the first match of the season against Reading on 12 August.
McClair turned out for the tournament in its 21st anniversary year in 2003 when he took a coaching session at the launch in Cultra, an event attended by both United manager Sir Alex Ferguson and England international defender Gary Neville.
"I have not spoken to (chief executive) David Gill about it but I'm sure there will be another contract because Gary's been back to his best, " said Ferguson.
Garrett scored from the spot after Ferguson challenged his former Linfield team-mate inside the area and then Gary Browne brought a brilliant save from Andy Coleman.