Lam has played a total of 35 international test matches, making him the second highest coming behind Tusi Pisi who has played a total of 37 matches.
Lam was one of the two players that were called back for a last minute fitness test before flying out to Japan.
He was replaced late in the first half of Saturday's 34-15 defeat by Australia in Parramatta after taking a knock to the eye while attempting to tackle Sekope Kepu, with Malolua following suit a couple of minutes later after dislocating his shoulder.
However, Lam passed the test.
Samoa will face Russia in their first game of the Rugby World Cup on 24 September 2019.