Lambert could miss Saints' trip to Swansea
The England striker has scored 11 times in the Premier League this term, helping Southampton to a guaranteed top-10 finish.
Southampton head coach Mauricio Pochettino, however, revealed that the 32-year-old may not feature in Saturday's clash at the Liberty Stadium.
"We have a doubt about Rickie Lambert and we need to assess him ahead of the game tomorrow," Pochettino said.
"We will see maybe if he can come on as a sub or it may be better to not risk him and keep him on the bench.
"He had a knock on his gluteus maximus last week and we need to evaluate whether he will be to take part or not."
Pochettino had more positive news of midfielder Morgan Schneiderlin, who could return after sitting out last weekend's 2-0 victory over Everton due to a knock.
"Morgan could make a return," the Argentina added. "He's been training well throughout the week, but we still need to assess him."
Swansea are safe following back-to-back victories - over Newcastle United and Aston Villa - and Pochettino is braced for a tough test against the Welsh side.
"They play good, attacking football," Pochettino continued. "Swansea are tough opposition but we'll be going out for all three points."