The Los Angeles Galaxy midfielder, who turns 34 in May, has been on good form during his loan spell at AC Milan and could equal Bobby Moore's record of 108 caps for an outfield player if he faces the European champions in Seville.
"David Beckham is here because he is playing well at Milan," Capello told a news conference on Tuesday.
"Perhaps he will play but I am not sure at moment," the Italian added. "I still have to choose the first 11."
Capello said Beckham was an important presence in the England camp, an opinion shared by captain John Terry.
"For the younger players to see him around the place is a fine example to everyone," Terry said.
"He is playing well at Milan and fully deserves his place in squad and team," he added, praising Beckham's will to win.
Capello said his priority would be to give less experienced squad members playing time and that he planned to make five substitutions.
"I prefer to test some of the players who have played only one or two games," he said.
"Some play very well for their clubs but not with the same confidence in the national team," he added.
"I want to see confidence and spirit in the team, the spirit of England. I want to play against all the teams in the world confident we can win and I want to see players without fear and with confidence."
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