Long has had a brilliant season for the Royals - scoring 23 goals - but has drawn a blank in his last four appearances and will be given the day off with the club's place in the play-offs secured.
Winger Jimmy Kebe has missed the last three games with a thigh injury and will again miss out, though he is expected to be fit for the start of the play-offs.
Forwards Mathieu Manset and Simon Church will be given starting roles as McDermott looks to end the regular season with a win.
Goalkeeper Adam Federici returned to the side for the goalless draw at Coventry last weekend and is set to keep his place after fully recovering from the knee injury which put him out of action for nine games.
Source: PA
Source: PA