England stars Theo Walcott and Daniel Sturridge missed their side's final training session ahead of Tuesday's World Cup qualifier against Ukraine.
Chelsea striker Sturridge and Arsenal winger Walcott complained of feeling unwell on Sunday and were absent when Roy Hodgson's squad went through their paces at Arsenal's training ground on Monday.
Hodgson will be keeping his fingers crossed that the duo recover in time for Ukraine's visit to Wembley as his squad has already been hit by a series of injuries over the last two weeks.
Wayne Rooney, Andy Carroll and Adam Johnson were all ruled out before Hodgson even named his squad, while Ashley Cole was sidelined for Friday's 5-0 win over Moldova and the Ukraine game wth an ankle injury.
To add insult to injury, Chelsea defender John Terry suffered an ankle problem against Moldova and will also miss the Ukraine game.
Hodgson will give an update on Sturridge and Walcott at his pre-match press conference later on Monday.