Callum Smith is the leading contender to face Saul 'Canelo' Alvarez on Sep.12, according to promoter Eddie Hearn.
Smith's fellow English boxer John Ryder, U.S.-based Irishman Jason Quigley, Ukrainian Sergiy Derevyanchenko and Canadian David Lemieux are also on the list of possible opponents for the Mexican, whose fights are shown by DAZN.
Billy Joe Saunders, also from England, who holds the WBO super middleweight title, has dropped out of contention after initially being lined up to face Alvarez before coronavirus closed down the sport in March.
Hearn believes Alvarez's preferred option is WBA super middleweight champion Smith (27-0, 19 KOs), 30, who beat Ryder in his last fight by a unanimous points decision in a second title defence in November.
Alvarez (53-1-2, 36 KOs), 30, holds a less prestigious version of the WBA super middleweight title and was boxing's third biggest earner over the last year according to Forbes -- behind heavyweights Tyson Fury and Anthony Joshua.
"If Canelo had the choice he would choose Callum because he wants to fight champions," Hearn said on Wednesday.
"Alvarez would like to get his hands on the WBA super belt and The Ring magazine belt. We have discussed a number but we are not there yet. There's a little stalemate, but Callum Smith is in training to fight Canelo and he is ready. We just have to get it over the line."
With fans still not allowed at boxing events, organisers may be influenced by a cheaper opponent like Ryder to balance the lack of a gate revenue. Southpaw Ryder (28-5, 16 KOs), 32, from north London, has had a resurgent two years after stepping up a division and many felt he should have got the decision over Smith. Ryder has looked stronger at super middleweight than at any time in his career, which has seen him lose four times at domestic level.
"They are two very different prices for those two opponents," Hearn added.
"John Ryder is definitely in the mix for that fight. If you are looking at the revenues coming in from the shows at the moment, there's a significant hole coming into a Canelo fight with no gate. It could be $6 million, it could be $10m.
When you have got an opportunity to save money on an opponent that is creditable and you feel it could be well accepted by broadcast partners and fans, that's attractive.
"I think John Ryder is someone fans and broadcasters would say he deserves his shot at the big time. He's definitely in the mix, but Alvarez would like to get his hands on the WBA 'super' and The Ring magazine belt but he will have to pay for that."
Another opponent who would be cheaper for the promoters and broadcasters is California-based Quigley (18-1, 14 KOs), 29, from Donegal, Ireland, who last fought in January and is also confident of getting the Alvarez call.
Quigley has compared it to his "Rocky moment" and, crucially, is promoted by Golden Boy, as is Alvarez.
Alvarez last boxed in November, when he knocked out Sergey Kovalev in the 11th round for the WBO world light-heavyweight title.
The Mexican has won world title fights at middleweight, super middleweight and light heavyweight over the last two years.