"He is fighting in September," Arum told ESPN. "I don't know against who and I'm not exactly sure where, but it looks like Macau or Singapore."
Pacquiao's potential opponents are Juan Manuel Marquez, welterweight titlist Timothy Bradley Jr. and Mike Alvarado.
"It will be one of those three guys, at 147 [pounds]," Arum said. "My idea would be if [Pacquiao] fought Marquez, we do Bradley against Rios if Rios wins."
In terms of a venue, the promoter told ESPN he's waiting for the Venetian Hotel management to decide which hotel they'd like to use for the fight.
According to Arum, Pacquiao's Asian fight would take place in the morning local time so as to accommodate a live prime-time HBO PPV broadcast in the United States.