Since neither guy is in the UFC this belongs in the Strikeforce section.
But honestly Fedor would mop the floor with Sergei. Kharitonov has long been overrated. The fight would be like Monson/Sergei except replace the choke with an armbar.
"If you get hit and it hurts hit him back you not knocked out yet."-Joe Doerksen
The Toxic Terrors (FFL)
Demetrious Johnson*Eduardo Dantas*Emanuel Newton*Will Brooks*Michael Page