The Brazil international was stretchered off in The Reds’ 2-0 win over Chelsea at Stamford Bridge on Tuesday night after a challenge with Ryan Bertrand, and he underwent tests on Wednesday.
The Anfield club have refused to comment on the injury until the results of the scan are returned, with the South American facing up to six months out should it be determined that there is damage to his cruciate ligament.
“I will have the scan to see how bad my injury is. Just send positive energy and I hope it won’t be too bad,” Lucas stated on social networking site Twitter.
The ex-Gremio battler has been a key man for Kenny Dalglish’s side this season, and has impressed with combative and determined performances in front of the Anfield back four.
Lucas has been an ever-present in the league this term, and has also played three games in the Carling Cup.
Meanwhile, Liverpool have recalled Jonjo Shelvey from his loan spell at Blackpool to act as cover for the period that Lucas will be on the sidelines.
By Gareth McKnight