Daniel Sturridge and Theo Walcott were absent from England's final training session ahead of Tuesday night's World Cup qualifier against Ukraine at Wembley.
The duo trained on Sunday but complained of feeling unwell overnight and did not participate in the session at Arsenal's London Colney training complex.
It left head coach Roy Hodgson with only 18 players to be put through their paces after the withdrawal of defender John Terry with an ankle problem.
A further update on the condition of Walcott and Sturridge will be given when Hodgson stages his pre-match press conference later on Monday.
Meanwhile, a weekend surge in ticket sales means 68,000 have been sold for the clash against the Ukrainians, the Football Association confirmed.
The figure includes 6,500 which have been sold to Olympic Games volunteers at the reduced price of £20.12.
At half-time, 15 Team GB medallists will be presented to the crowd.