During a news conference Wednesday, UFC president Dana White revealed the promotion's plans to host a June meeting between the two inside a soccer stadium in Rio de Janeiro.
UFC co-owner Lorenzo Fertitta told ESPN.com via text that while a deal hasn't been finalized for the event, it could be pending.
"It's not locked down 100 percent," Fertitta said. "But close."
Officials have not confirmed which venue would serve as host. Estadio Olimpico Joao Havelange, also known as Engenhao, is one possible destination.
The event figures to break the company's attendance records last set at UFC 129 in April 2011. That event, held at Rogers Centre in Toronto, drew a crowd of 55,724 and pulled a live gate of $12.075 million.
White estimated the Rio card could draw as many as 80,000. Silva is Brazilian.
"This thing's going to be in a soccer stadium in Rio," White said. "Over 80,000 people are going to be at this event."
Speaking on "UFC Tonight" earlier in the week, Sonnen revealed he has not yet signed a contract to face Silva, although he added he expected the fight to take place in June.
The two fought in a fight of the year candidate in August 2010, with Silva retaining his belt via submission in the final two minutes.