Lampard suffered the injury at England's Buhlertal training ground on Thursday in a closed-doors session as they prepared for Saturday's game at Gelsenkirchen.
"He did turn his ankle yesterday in training," a Football Association spokesman said on Friday. "But I've spoken to Frank this morning, he feels fine and he expects to train."
The session will be held later in the day at Gelsenkirchen stadium, with Lampard's fitness likely to be a topic for coach Sven-Goran Eriksson at a subsequent news conference.
Though Lampard has yet to score at these finals, he is a key attacking figure in the five-man midfield which Eriksson is expected to deploy against the Portuguese.
Lampard, who hit 20 goals for Chelsea last season on their way to the Premier League title, had scored 10 times in his previous 22 games for England before the tournament.
