Liverpool's Lucas out for up to three months
The 25-year-old Brazilian was substituted after five minutes of last weekend's 2-2 draw against Premier League champions Manchester City.
"The indications are two to three months. It is quite a unique injury at the top of his right thigh," Rodgers was quoted as saying on the Sky Sports website.
"He has had a scan and we will see a specialist this evening. We'll see if it needs an operation or whether it is just recuperation."
Lucas missed most of last season after suffering a knee ligament injury in November.
"No words to describe my feelings at the moment. It is been hard to be positive but I am sure better days will come," Lucas said on Twitter.