Tom Cleverley was stretchered off during Saturday's 0-0 draw with Tottenham Hotspur at White Hart Lane.
The Everton boss said there was no fracture to his leg after a challenge with Eric Dier towards the end of the first half of the game, and admitted that he feared the worst after seeing the midfielder in agony on the field. He has yet to put a timescale on the England international's recovery.
He told the club's official website: “We thought that it was a fracture and to have a fracture at this stage of the season for Tom would have been devastating because his form has been terrific.
“He has got ligament damage and the next step will be to see how long he is going to be out.
"It’s an injury we need to try and recover as quickly as we can but clearly it’s good news from when we saw Tom falling to the ground at White Hart Lane.”
Regardless of how long Cleverley is out for, it's a blow to get injured so early on in his Everton career when he seemed to be putting in some impressive performances following his free transfer switch over the summer.
Over the past couple of years, Cleverley was a source of ridicule for some, especially during a poor season for Manchester United, but seemed to find some form towards the end of last season while on loan at Aston Villa, and started his Everton career in a relatively positive fashion.
Damage to ankle ligaments is hardly ideal at this stage, but it is preferable to a broken leg, therefore it is understandable to see why there is an element of relief in Martinez's comments.