Walcott has become the latest player to drop out of the England squad after being sent home with a virus.
London: Winger Theo Walcott has become the latest player to drop out of the England squad for Tuesday's World Cup qualifier against Ukraine at Wembley after being sent home with a virus.
Chelsea defenders Ashley Cole and John Terry had to withdraw from the squad over the weekend with ankle injuries to join Wayne Rooney, Andy Carroll, Gareth Barry, Ashley Young and Scott Parker on the sidelines.
Coach Roy Hodgson told a news conference on Monday that striker Daniel Sturridge was suffering from stomach cramps but could be fit for the Group H match.
Given the illness in the camp, uncapped duo Raheem Sterling of Liverpool and Adam Lallana of Southampton have been added to the squad along with Tottenham Hotspur midfielder Jake Livermore.
"Theo has picked up some sort of virus or bug because he was quite violently ill last night. Daniel trained yesterday with stomach cramps and complained of them but still got through the training session," Hodgson said.
"Today he woke up with the same sort of cramps although he was slightly better I believe and the doctor is confident he will be OK."
The only change Hodgson was expecting to make from the side that beat Moldova 5-0 in their opening qualifier on Friday was choosing either Gary Cahill or Phil Jagielka to replace Terry in the centre of defence.
"I don't need to be coy about the team - John Terry's position will be taken by either Phil Jagielka or Gary Cahill. There won't be any other changes unless something untoward happens between now and Tuesday," he said.
Skipper Steven Gerrard, who made his international debut against Ukraine in 2000 and will win his 98th cap on Tuesday, was delighted a crowd of around 70,000 are expected for the London match.
"It will be one of the highest attendances throughout Europe and on the back of the Olympics and the Paralympics, it's incredible really," he said.
"The performance (against Moldova) the other night was positive, but I think tomorrow night will be an even bigger test.
"They are a group of players who have been together for a long time and are technically very good and there were times when we played them in the Euros that we stood off them and gave them too much respect."
England, who beat Ukraine 1-0 in Donetsk on June 19, are unbeaten in eight matches under Hodgson and have only lost two of the 40 World Cup matches they have played at Wembley.
England are top of the early standings in a group which as well as Ukraine and Moldova includes Poland, San Marino and Montenegro.