Their involvements were confirmed during a press conference held in Manilla for the event, which will see Pacquiao challenge for Matthysse's WBO World Welterweight title at the Axiata Arena.
The contest between Matthysse and Pacquiao will be Malaysia's first world title match since 1975, when Muhammad Ali defeated Joe Bugner at the Merdeka Stadium.
Farkhan, currently holding the WBC Asia Silver Cruiserweight, WBC Asia Light Heavyweight and ABF Cruiserweight belts with a 6-0 win record, will lace up in a light heavyweight bout.
As for Theena, who is 5-0 in the ring ever since bursting onto the professional boxing scene with a 25-second KO win, will be in a welterweight fight.
However, both of their opponents have not been confirmed.
Three other title fights are also on the undercard, including a bout between Pakistan's Muhammad Waseem and South Africa's Moruti Thalane for the vacant IBF flyweight world title.
There will be 4 world title fights in the “Fight of Champions” on July 15 in Kuala Lumpur, which will be headlined by the Manny Pacquiao-Lucas Matthysse bout for the WBA regular welterweight title. #PacquiaoMatthysse @RapplerSports pic.twitter.com/Da7e7JJOHX
— delfin dioquino (@dioquinodelfin) April 18, 2018