Diakiese (13-3) recently snapped a three-fight skid by winning a unanimous decision over Joseph Duffy at UFC London this past March. The 26-year-old Englishman won his first 12 pro bouts, including his first three in the UFC, before slumping.
Vannata, 26, who sports one of the strangest UFC records at 2-3-2, is coming off of a first-round submission over win over Marcos Mariano at UFC 234. Prior to that victory, he recorded two draws in three appearances, fighting Matt Frevola and Bobby Green to a stalemate. His overall pro record stands at 10-3-2.