Now that Parker has defended his title in a mandatory challenge, he is free to fight a voluntary against an opponent of his choice.
There are several options - a unification fight against one of the other title holders would in theory be desirable, but that is unlikely to happen in the short term.
Parker remains on a collision course with WBA, IBO and IBF title holder Anthony Joshua, but that fight will probably be allowed to build in order to increase anticipation.
Parker will probably fight again in December.
The options include:
Kyotaro Fujimoto (Japan):
Parker's promoter David Higgins likes the idea of fighting Fujimoto, who is ranked No9 with the WBO because the 31-year-old has a 17-1 professional record and would be considered a relatively easy night in the ring. Even more alluring is the fact that Japan have never had a heavyweight challenge for a world title and that could create interest there, which equals views and revenue.
Dillian Whyte (England):
Whyte has been quick to challenge Parker and a fight against him makes good sense for Parker. Whyte, 29, nicknamed 'the Body Snatcher' as a 21-1 record and is ranked at No10 by the WBO but in reality is at several levels below as an elite heavyweight. Crucially, Whyte has a relatively high profile in the UK.
Deontay Wilder (USA):
The Bronze Bomber is the WBC champion with an extraordinary record of 38-0 record, including 37 knockouts. He is fighting Luis Ortiz in a title defence in November which would make him a very unlikely opponent for Parker next up, but he's one that Parker's camp will be eager to get in the ring with. Wilder is a wild, unorthodox puncher but has never truly been tested.