Vermaelen impressed during Arsenalâ€™s 0-0 draw against Chelsea last night, which was just his second League start of the campaign.
Walcott told the London Evening Standard: â€œHe can have a big part to play in our season, without a doubt. Itâ€™s a great thing at this club that we have a lot of competition for places now.
â€œThomas wanted to prove a point and Iâ€™m sure the way he played against Chelsea, he is definitely in the managerâ€™s thoughts now.
â€œIâ€™m very happy for him, he was fantastic and helped get us a clean sheet and that will give him a lot of confidence. Thomas will want to make that position his own."