Patosi received a first international call-up for the game at the Moses Mabhida Stadium on December 22 after a fine season in Belgium, where he has emerged as a genuine star of the league.
But such is his importance to his club that Lokeren say they will not release him for the game as they face Darren Keet's Kortrijk on December 21.
Lokeren also have a league match against Cercle Brugge on December 26, their last before the winter break, meaning the earliest he could likely link up with the Bafana squad is on December 28.
"We will not allow him to go, he is too important for our team," said Lokeren sporting director Willy Reynders. "We need Patosi against Kortrijk."
Lokeren are under no obligation to release Patosi as the match against Malawi falls outside of the Fifa match calendar.
Teams are only required to release players two weeks before the start of major continental championships, meaning January 5 for the 2013 Africa Cup of Nations.
It is a blow for the player, who is trying to convince national team coach Gordon Igesund that he deserves a place in his Nations Cup squad.
As Igesund is due to announce his final selection for the tournament on December 30, that would give him two days in camp at best.
Patosi has scored six goals in 19 starts for Lokeren this season, including a wonder-strike that went viral and brought him to the attention of the world.