Source: Thiago Silva back in UFC in May
The Silva-Pokrajac bout is tentatively scheduled for May 15.
Pokrajac replaces Brandon Vera, who withdrew from the fight due to an undisclosed injury.
Silva (14-2, one no contest) returns to action for the first time in 16 months, due to a year-long ban. He was suspended by the Nevada State Athletic Commission after it was discovered that the Brazilian altered his urine test before a bout with Vera on Jan. 1, 2011.
Though Silva defeated Vera by unanimous decision, the bout's result was later changed to a no contest.
Pokrajac (24-8) has won three of his past four fights. In his most recent outing on December 11, he knocked out Krzysztof Soszynski in the first round.
Franklin McNeil covers mixed martial arts and boxing for ESPN.com. Follow him on Twitter at www.twitter.com/Franklin_McNeil.