Bellator announced the details on Wednesday night.
In February, Shlemenko captured the title vacated by Hector Lombard when he left for the UFC. He did so by knocking out Maiquel Falcao in the second-round. That victory marked his 10th straight, improving his career record to 47-7.
His opponent Marshall is a surprise challenger, having lost three of his four fights before making his Bellator debut. Since joining the promotion however, Marshall (18-6) has been on fire, winning all four of his bouts, including three by first-round knockout. He worked his way through the season eight tournament by defeating Andreas Spang, Sultan Aliev and finally, Brett Cooper.
The three-hour Sept. 7 event will take place on Saturday, but the season will shift to Fridays in the weeks to follow. The night's card will also include the finals of the "Fight Master" season one tournament.