Marcus Rashford was the only absentee from England training a day out from their opening Euro 2020 qualifier against the Czech Republic.
The Manchester United striker is nursing an ankle injury that leaves him a slight concern for the visit of the Czechs to Wembley on Friday night.
Rashford, capped 31 times by his country, with six goals, had an individual session indoors at St George's Park as he bids to prove his fitness.
The 21-year-old has become an integral part of Gareth Southgate's line-up, scoring three times in his last six international appearances.
England's official Twitter account posted: "21 players are taking part in today's session, with @MarcusRashford working separately to the main group."
He is the latest injury headache for Southgate, who has already had five players withdraw from the squad for the Group A double header against the Czechs and Montenegro.
On Wednesday, Liverpool full-back Trent Alexander-Arnold pulled out because of a back complaint, with Fabian Delph, John Stones, Luke Shaw and Ruben Loftus-Cheek already ruled out.
Promising Chelsea teenager Callum Hudson-Odoi has been brought in despite having not yet made a league start, with Southgate also turning to in-form Southampton midfielder James Ward-Prowse.