Walcott was injured in a challenge with Birmingham's Liam Ridgewell last weekend
Arsenal manager Arsene Wenger has rejected suggestions that winger Theo Walcott is injury prone after he was ruled out for up to four weeks.
The 20-year-old, who missed the start of the season with a back problem, was replaced after 33 minutes on Saturday after suffering knee ligament damage.
Walcott also spent much of last season out injured, but Wenger is unconcerned.
"He is a young boy and you sometimes go through a period like that when you are that age," said Wenger.
"When your body settles and adapts as you get older then usually you have no problems any more. But because he is pacy then he is a bit more exposed."
Walcott returned to action for his club this season as a substitute against Blackburn on 4 October and featured in England Under-21s 6-3 win over Macedonia five days later.
He made a bright start against Birmingham on Saturday at the Emirates Stadium but required treatment following a robust challenge by Liam Ridgewell and, despite returning to the field, was soon forced to make way. It was his first Arsenal start of the season.
Walcott will play no part in Arsenal's Champions League fixture away to AZ Alkmaar on Tuesday and could miss games against West Ham, Liverpool in the Carling Cup, Tottenham, Alkmaar in the return fixture and Wolves.
The winger may also struggle to be fit for England's friendly against Brazil in Doha on 14 November.
"The news is not good because we thought it would be just 48 hours but it is a medial knee ligament, which is what I feared after the game," added Wenger.
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