"He trained this morning and looked very, very good," McClaren said in a news conference on Tuesday.
The friendly at Wembley is preparation for England's Euro 2008 qualifiers at home to group rivals Israel and Russia next month and McClaren said he was happy to have Beckham, now with LA Galaxy, back in the squad with him set to win his 97th cap.
"We've said right from the beginning he's back in the squad because of his performances, he'll stay in the squad because of his performances and he'll play because of his performances and that's it," said McClaren, who axed the former captain from the squad after the 2006 World Cup finals.
"We'll monitor his progress in LA in the MLS and we'll monitor it when he's here."
McClaren has already had to contend with several withdrawals, including midfielders Steven Gerrard and Owen Hargreaves, while Everton striker Andy Johnson pulled out on Tuesday with a knee injury.
Wayne Rooney is missing with a broken foot while Peter Crouch is suspended for the match against Israel and so would be unlikely to start.
NO LIMITS
Michael Owen, who came on as a substitute for Newcastle United on Saturday, will feature, with Jermain Defoe and Alan Smith also likely to play at some stage.
"It's an ideal game for him to get some minutes under his belt," said McClaren, who confirmed that no Premier League managers had set any limits on the amount of time their players should spend on the pitch.
"I've got no qualms about picking the team," he said.
Defeat in Croatia last year and draws against Israel and Macedonia have left England fourth in Group E, three points behind Croatia and Israel and one behind Russia.
They play Israel on Sept. 8 and host Russia four days later.
"We've cleared the (players') heads, told them we're in a great position to qualify," McClaren said. "This is an important game in preparation for Israel and Russia."
England have only met a unified Germany nine times in international football, the last occasion being in 2001 when England won a World Cup qualifier 5-1 in Munich.
They played West Germany on 16 occasions, the most famous meeting being the 1966 World Cup final and the rivalry makes any meeting, even a friendly, a eagerly-anticipated prospect.
The Germans beat England 1-0 in the last match played at the old Wembley Stadium in October 2000 before it was demolished.
After Brazil were England's first opponents at the new stadium in June, the Germans are the first Europeans to face England there.
Germany have beaten England four times at Wembley -- more than any other foreign country.
With 90,000 at the stadium and millions more watching on TV, skipper John Terry confirmed the players felt no match against Germany was "just" a friendly.
"We can't class it as a friendly game and we are looking forward to putting on a show. Once we're out there we want to get amongst them," Terry told reporters. "I know what facing Germany means to England fans."
On David Beckham's jet-setting schedule, Terry added: "I've spoken to him and he's fine ... he's a great professional. He's getting his sleep in and he will deal with it in his own way."
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