(TV: Fox Soccer Channel, live, 3 pm ET.)
McClaren says he will "stand or fall" by his decision to recall Beckham.
When he took over for Sven Goran Eriksson after the World Cup, McClaren dropped Beckham, but he changed his mind after Beckham's recent return to form.
"I have looked at David since the New Year and watched him very closely," McClaren says. "He looks very fit, the fittest I have seen him for a long, long time."
McClaren's decision comes after England has struggled in Euro 2008 qualifying. It faces a must-win game when it travels to Estonia next Wednesday.
"I have to be pragmatic," McClaren adds. "Everyone knows we need to win in Estonia next week. The squad I have selected is designed to do that."
McClaren has tried to downplay Beckham's return, insisting that his star not talk to the media before the game.
"When I spoke to David two weeks ago, we agreed to try and keep everything low key," says McClaren. "I know him well enough and I know he just wants to play. That is why he doesn't want to speak to anyone.
"Sometimes the attention surrounding David can run out of control but that is not his fault, it is just the hype that surrounds him. We just want David Beckham the player, performing on the pitch and that is all we are going to focus on for the next 10 days."
McClaren will be without central defender Rio Ferdinand for both the Brazil and Estonia games due to a groin injury. He is likely to be replaced by Liverpool's Jamie Carragher alongside Chelsea's John Terry in the middle of the England defense.
Some experts will argue that more important than the return of Beckham is the comeback of Michael Owen, who is set to start for England for the first time since suffering a knee injury at the 2006 World Cup that sidelined him for most of the EPL season.
England's attack has struggled in Euro 2008 qualifying. Besides eight goals in two wins over tiny Andorra, the Three Lions have only one goal in four qualifiers.