Manchester United striker Danny Welbeck and Tottenham defender Kyle Walker missed training on Monday morning ahead of England's upcoming friendly double-header.
Both players were able to take part in a gym session though, raising hopes they could feature against Republic of Ireland at Wembley on Wednesday or in Sunday's high-profile match with Brazil in Rio de Janeiro.
Walker is understood to have picked up an injury during Spurs' end of season friendly against Jamaica in the Bahamas last week.
England are expected to reveal the nature of the injuries later on Monday.
Joe Hart, Joleon Lescott and James Milner all took part though, despite having only just returned from Manchester City's end-of-season tour of the United States.
Gary Cahill, Ashley Cole and Frank Lampard, who were part of the Chelsea squad that faced City in games in St Louis and New York, also trained.
Uncapped Reading goalkeeper Alex McCarthy was tested in the session at St George's Park, saving shots from fellow goalkeepers Hart and Ben Foster.