Speaking on the latest edition of the Knees Up Mother Brown Podcast Sullivan revealed that the former Arsenal star is set to return to the Boleyn Ground if he passes a medical before the transfer deadline.
But the outspoken chairman has admitted he hopes the 'real' Alex Song turns up for West Ham this season if and when the deal goes through, saying the former Cameroon captain was distinctly average in the second half of last season.
Deal in place
"We have a deal in place with Alex Song subject to a medical," Sullivan told the KUMB Podcast.
"On his pre-Chistmas form he was possibly the best player we've ever signed.
"But after Christmas he was just another player.
"Maybe there's reasons for that and maybe we'll see the true Alex Song and maybe he'll make a huge contribution this year."
Sullivan's comments are not far wrong and most Hammers fans would agree with his assessment of the player.
Song played 28 games last season and early on there was a running joke on the terraces that the Man of the Match could be named before kick-off given the number of times he had won the award.
Former West Ham favourite Trevor Sinclair also took to Twitter to echo Sullivan's sentiments on Song saying: "Let's pray West Ham sign the Alex Song from the first half of last season rather than his brother from the second half."
Shock move was the right move
Song completed something of a shock move to East London last August in search of more game time and to kick-start a career which had been stunted at the Camp Nou.
But niggling injuries hampered his form and it had a direct impact on the team as the Hammers dropped like a stone in the new year to finish 12th.
Singing Song's praise
Now with a new manager in place, Sullivan recently admitted he was trying to get the ex-Gunner back to fire up the club's midfield on a permanent basis.
"Look, we know what Alex Song is and it also shows the size of the club," Bilic told West Ham's official website.
"If someone had told you three years ago that Alex Song will play for West Ham very few people, apart from the fans of course, would believe it."