Claudio Ranieri's side have enjoyed a fairytale season and currently sit five points clear of nearest challengers Tottenham and Arsenal with 13 games of the campaign to go.
Last weekend's 3-1 victory over Manchester City put Leicester in pole position to win their first ever top-flight title, and Martinez believes the Foxes are now clear favourites, provided they can keep their squad free from injuries and suspensions.
"At the moment it's impossible to tell [who's going to win the league], it's the most open league I've been involved in," he told reporters.
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"For me, if you were going to guarantee a starting XI, I think it is for Leicester to lose it. But you can't guarantee everyone will be fully fit or not suspended.
"But I feel now the title is for Leicester to lose, it would be an incredible achievement."
Meanwhile, Martinez has rubbished speculation that Phil Jagielka could leave the club following reports that he could follow the likes of Ramires and Jackson Martinez to China.
"We are not in a situation to lose any players and Phil Jagielka is our club captain," he added. "He has been [playing] at a good level and there is no substance in that rumour.
"I can guarantee you that no-one is going to leave between now and the end of the season, unless it's on a loan period to the Championship for a player we feel needs playing time.
"Any speculation is a waste of time."