Diao awaits the results of a scan today and Babbel will be checked over by the club's medical staff.
"Salif Diao got a bad kick on his ankle which is also very sore and we will scan him as well," said Gerard Houllier.
"Markus Babbel has a bit of a twist in his knee. We are hoping it's not a medial ligament injury but we will see on Sunday.
"Florent Sinama Pongolle also took a bit of a knock but he should be ok."