The 24-year-old scored England's first goal in the 3-2 win at Wembley on Wednesday evening but was forced off after 75 minutes complaining of a swollen knee.
There were fears the injury could keep him out of Arsenal's season curtain raiser at the Emirates Stadium on Saturday.
However, the former Southampton youngster was quick to play down the severity of the knock after the game and is confident he will recover in time for the weekend.
"Hopefully, fingers crossed, I'll be alright," he told Sky Sports. "I had to come off with a little bit of a swollen knee so fingers crossed I can rest up and I'll be alright for Saturday."
Looking ahead to the new campaign, Walcott added: "Everyone dreads pre-season so this is the most important time.
"This is a big year for Arsenal and myself."