Sturridge missed England's 2-1 win over Australia in Sunderland on Friday after sustaining a calf strain during Liverpool's Europa League final defeat by Sevilla.
Victorious Real Madrid get heroes welcome in Spanish capital
But the 26-year-old emerged for training with the rest of his team-mates at Watford's training ground on Monday.
Sturridge's place in the squad is thought to be under threat, with 18-year-old Manchester United striker Marcus Rashford having marked his debut with a goal against Australia.
Southampton left-back Ryan Bertrand, who is nursing a knock, was the only injury-enforced absentee on Monday, which left 24 players training.
Local rivals: Madrid’s finest collide as Spain rules Europe
Chelsea centre-back Gary Cahill trained after missing Friday's game because of a hip problem.
Manchester City midfielder Fabian Delph has already dropped to the standby list due to a groin injury.
England play Portugal at Wembley on Thursday in their final warm-up game before travelling to France next week.
They open their Euro 2016 campaign against Russia in Marseille on June 11 and will also face Slovakia and neighbours Wales in Group B.
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