Since coming back into the side however, Leeds have captured some sort of form and he will be badly missed in the fight against relegation.
United's Head Coach Kevin Blackwell told the club's official website: "He has torn his hamstring completely, he heard it snap straight away and it's a bad injury.
"To lose Lucas is a massive blow because he is such a big influence in the side.
"We've not had him in the side for most of the season through injury, we get him back we start doing well and it's no coincidence, but now we've lost him for up to nine weeks.
"He's a major influence with his desire and his passion and from week to week he just gets out there and plays. He puts his head in where it matters and is such a great ambassador to himself.
"We're just so sick that we've now lost him for such a long period of time."