Steven Gerrard was among four high-profile absentees from training on Tuesday morning as the debate over his availability for England's crucial Euro 2008 double-header with Israel and Russia continues.
The Liverpool captain has played only once since breaking a toe against Toulouse three weeks ago and Reds boss Rafael Benitez has expressed doubt as to whether Gerrard will be fit for both games.
However, the England coach decided to let Gerrard continue his rehabilitation in the gym as the rest of his squad were put through their paces for the first time at Arsenal's London Colney training complex.
Captain John Terry was also absent after reporting for duty on Sunday night feeling slightly under the weather.
Manchester United's Owen Hargreaves was also restricted to gym work as he continues to battle against a tendonitis problem in his knee which has affected the start of his Red Devils career.
McClaren is confident both Terry and Hargreaves will train on Tuesday, which will be a welcome relief considering the uncertainty over Gerrard and the news that Frank Lampard has effectively been ruled out of Saturday's encounter
with Israel at Wembley.
The midfielder did link up with the England squad as planned but after a quick assessment by the FA's medical staff, the 29-year-old was sent back to Chelsea.