"I was surprised," a smiling Capello told reporters at Wembley, when quizzed about the 34-year-old's award on the night that he took his tally of England caps to 115.
"For 30 minutes? It's like Obama winning the Nobel Prize after just nine months as the President of the United States."
Former captain Beckham, who did not even make the bench in the 1-0 defeat in Ukraine on Saturday, also said he was a "bit embarrassed" to be named man of the match after spending most of the game warming up to high-pitched shrieks from young fans.
However, Beckham, who confirmed that his loan move to AC Milan from LA Galaxy is close to being finalised, showed when he replaced winger Aaron Lennon just why he will probably be in Capello's 23-man squad for next year's finals in South Africa, providing quality service with his trusty right foot.
While Shaun Wright-Phillips and Lennon did plenty of scuttling around, neither could find the poise that the former Manchester United and Real Madrid midfielder supplied.
His quick thinking from a corner straight after coming on opened the way for Shaun Wright-Phillips to make it 2-0 and clinch a ninth win in 10 Group Six matches for England.
"Whether David Beckham plays for five, 10, 15 minutes or half the match he always plays with lots of focus," Capello said. "Some players find it hard to come on but Beckham does that very well."
Beckham, sporting a bushy beard, said he was taking nothing for granted but insisted he would fight for his place in what would be a fourth World Cup finals with England.
"Fabio Capello knows the situation with me," he told reporters. "There is still a long way to go before the finals. What I will do is work hard and play as hard as I can and make sure that I give myself a chance."
(Editing by Ed Osmond)