The UFC announced Wednesday that health issues have forced Alexander Volkov out of his scheduled meeting with Alistair Overeem at UFC St. Petersburg on April 20 and that Volkov will now be replaced in the headlining spot by Oleinik (57-11-1). ESPN was first to report the change.
Oleinik had previously been booked to fight Walt Harris at UFC Ottawa on May 4. Per the release, a new opponent will be found for Harris.
In his last outing, the 41-year-old Oleinik defeated Mark Hunt by first-round submission in the main event of UFC Moscow last September.