Speaking at his weekly press conference, the Reds boss revealed that everybody who featured against Real Madrid in the Champions League on Wednesday has returned to M16 in rude health and is in contention to start against the Royals.
However, with important fixtures in Europe and the Barclays Premier League coming up, Sir Alex will utilise the strength-in-depth at his disposal - though he is not taking Brian McDermott's men lightly.
“We've come through Wednesday's game without any injuries,” the boss told reporters. “That's the best thing, apart from the result of course. I'll make some changes for Monday night, even though it’s an incentive to get to the quarter-final. I don’t think that’s lost on any of the players.
"There's a good spirit in place and they're all contributing. Whatever side I pick we’re expected to qualify. That's what happens at United. Whatever team you play you’re always expected to win. I went to see Reading last week and they’re a team who are showing plenty of fighting qualities at the moment, as you’d expect given they’re down the bottom of the league.
"We'll take nothing for granted. In the FA Cup you always expect the unexpected. It happens so many times. You just hope you're not a casualty or a shock. We've had a few over the years. But I can't be more pleased than I am at the moment with the form and spirit in the place. It’s good."
Sir Alex also revealed that Paul Scholes is struggling with a knee injury and could be out for a couple of weeks.