TORONTO - The main event at UFC 140 in Toronto should be announced in the next "three to four weeks."

That's the word from UFC chairman and CEO Lorenzo Fertitta, who downplayed the rumours that former heavyweight champ Brock Lesnar would meet Alistair Overeem at the Air Canada Centre on Dec. 11.

"We don't know exactly what Brock's medical status is," Fertitta said. "He is going to be back, he is going to fight again, we just don't know if that timing is going to work out. We're talking to a lot of different people. There are going to be different possibilities but we'll definitely deliver."

Lesnar announced Thursday on his Twitter account that he had surgery recently to correct a problem related to his second bout of diverticulitis. He hasn't fought since losing his title to Cain Velasquez in October 2010.

The last time the company came to town, UFC 129 drew 55,724 fans to the Rogers Centre as Canadian star Georges St. Pierre posted a unanimous decision win over Jake Shields.

It's unlikely St. Pierre will be the headliner again, though.

"We're trying to put the final touches on it," Fertitta said. "Of course, coming back to Toronto we want to put on a big event. We've got some good ideas in the works."