Kolvalchuck was hurt late in the first period Wednesday when he scored his 38th goal this season in the Thrashers' 4-1 victory against the Pittsburgh Penguins.
He left the contest and did not return.
"He's a lot better today," Coach and General Manager Don Waddell told the Atlanta Journal Constitution Thursday.
Waddell added that Kovalchuk's absence in games Friday against the Buffalo Sabres at home and Saturday at Washington is more of a precautionary measure.
His goal total is second to Washington left wing Alexander Ovechkin.
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