England are sweating on the fitness of Theo Walcott and Daniel Sturridge ahead of the clash with Ukraine after they sat out Monday's final training session.
The duo trained on Sunday but complained of feeling unwell overnight and did not join in with the rest of the squad 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 due to an ankle problem over the weekend.
A further update on the condition of Walcott and Sturridge will be given when Hodgson stages his pre-match press conference.
Walcott came on as a substitute as the Three Lions kicked off their World Cup qualifying campaign with an emphatic 5-0 victory over Moldova on Friday, while Sturridge remained on the bench.
England can take a firm early grip at the top of Group H by beating Euro 2012 co-hosts Ukraine at Wembley on Tuesday.