Kamaldeen Sulemana was in action for Southampton in their narrow 1-0 defeat at Leeds United on Saturday.
The Ghanaian international started the game and was replaced by Diallo three minutes past the hour mark.
Junior Firpo scored the only goal of the game in the 77th minute to condemn the Saints to their fourth defeat in their last five Premier League fixtures.
Meanwhile, compatriot Mohammed Salisu missed the game through injury.
Southampton remain bottom of the standing with just eighteen points after 24 rounds of matches.
