Lampard facing three week layoff
Lampard picked up the injury on Thursday while training with England ahead of Saturday's friendly against Brazil in Qatar.
"The midfielder reported back this morning having flown back from the Middle East," the club said on their website.
"The Chelsea medical department's initial impression is he may take approximately three weeks to recover."
If confirmed, the absence will be less than initially feared after some media reports suggested Lampard could be absent for up to seven weeks.
Chelsea are five points clear of Arsenal and Manchester United in the league but have this week lost defenders Jose Bosingwa and Ashley Cole to injury.
Captain John Terry is also a doubt for England's friendly against Brazil on Saturday with an ankle problem.