Pacquiao was last in action at the same venue in June, losing the WBO welterweight title to American Timothy Bradley in a controversial split decision.
And the Filipino, who has held world championships in an unprecedented eight weight classes, will compete inside the famed casino and fight venue for the fourth consecutive bout towards the end of 2012.
Promoter Bob Arum told 8 Count News that though Pacquiao’s next adversary had been decided, he was under strict instructions to remain tight-lipped for the time being.
“We're not in liberty to tell you who [he's fighting]... that's my instructions,” Arum said.
When asked if he was frustrated by the delays, Arum said: “It's just part of the business, why would I be frustrated?
“December is a long, long time so we have plenty of time. Manny will be coming over to this country by 14-15 of September so we'll do the tour and the press conference right after the Chavez-Martinez fight.”
Mexico’s Juan Manuel Marquez, whom Pacquiao has fought three times already, is regarded as the favourite to step back into the ring with his long-running rival.
The third and most recent bout between the two took place at the MGM in November last year and was won by Pacquiao on a majority decision.