The Three Lions will meet Les Bleus in the quarter-finals of the 2022 World Cup if both nations progress from their upcoming last-16 games against Senegal and Australia respectively.
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Many consider Paris Saint-Germain superstar Mbappe to be the most dangerous player in Qatar and the 23-year-old backed that up with three goals and one assist in the group stage.
However, Walcott believes England may have the perfect weapon to nullify the Frenchman.
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Man City right-back Walker returned from a long-term injury during the 3-0 victory over Wales - and the 32-year-old is one of the few players in world football who could possibly match Mbappe for pace.
In his pomp, Southampton star Walcott was among the Premier League's fastest players and he has faced Walker on a number of occassions.
When asked whether Walker should man-mark Mbappe in a potential quarter-final showdown, ex-Arsenal star Walcott told talkSPORT: "I would love to see it. I really would.
"I feel like Mbappe would struggle against his [Walker's] physicality, if I'm honest.
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"He plays in the French league, which is a different kettle of fish to the Premier League and Walker has so much experience in the Champions League.
"So it would be a great test. I think we all want to see it.
"I couldn't tell you who would win that - because Mbappe is a different beast, he's on a different level at the moment."
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Despite a 0-0 draw with USA, England breezed through the group and sealed top spot with resounding victories over Iran and Wales.
Walcott, who was selected for the 2006 World Cup with the Three Lions, insists there will be tougher tests to come.
He added: "International football is very difficult at any level - but I don't think we've been tested properly at the back yet.
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"But we've been solid and it's coming."