The left-back's injury has left England boss Roy Hodgson with just one recognised left-back - Arsenal's Kieran Gibbs - to choose from for Saturday's Euro 2016 qualifier against Slovenia at Wembley.
Hodgson's England counterpart Roberto Martinez will have also been anxious to learn the severity of Baines' problem with other left-back options Bryan Oviedo still regaining fitness after a broken leg and Luke Garbutt having only one Premier League appearance under his belt.
Though Baines remains a doubt to return for Everton against West Ham after the international break, his participation has not been ruled out after suffering a grade one strain - recoveries from which are typically measured in days rather than weeks and months.
An Everton statement confirmed: "Leighton Baines could be in contention to face West Ham United next weekend after scans revealed the full-back’s hamstring injury is not as serious as first feared.
"The 29-year-old was forced to withdraw from the England squad yesterday [Friday] after pulling up in training with the problem.
"He returned to Finch Farm for an assessment which has since showed that he has sustained a ‘grade one’ hamstring injury – the least significant on the scale of such injuries.
"Baines will continue to be monitored by Everton’s medical team and, although he remains a doubt for next Saturday, he has not yet been ruled out of the game against Sam Allardyce’s Hammers."
