The England defender was hurt near the end of Everton's 1-0 Premier League loss to Sunderland on Thursday and missed the 2-1 victory over Southampton on Sunday.
"It happened at the end of the game against Sunderland," Martinez told reporters.
"With this soft tissue injury it could be up to four weeks, but knowing Jags he will be back earlier.
"It is just the accumulation of games and the demands of this month. November into December is high-risk in terms of injuries to the players."
Victory over Sunderland lifted Everton to fourth in the standings, five points behind leaders Arsenal at the halfway point in the season.
(Reporting by Ed Osmond, editing by Rex Gowar)
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