Abner Mares, who was stunningly knocked out in the first round and lost his featherweight world title to Jhonny Gonzalez last Saturday night in Carson, Calif., has exercised his contractual right to an immediate rematch.

"When we prepared the contract with Golden Boy, I made sure we had a rematch clause," Frank Espinoza, Mares' manager, told ESPN.com on Thursday.

Espinoza said he hopes that the bout can take place in December and is talking to Golden Boy chief executive Richard Schaefer about a deal.

"Abner wants the rematch," Schaefer said. "He has a rematch clause and wants to do it before the end of the year. Abner called me himself and said, 'I want to set the record straight and exercise my rematch option. This was nothing, it wasn't a fight. I want to fight the guy again and I want to take care of it this year.'"

Schaefer promotes Mares but also picked up options on Gonzalez's next two fights as part of the deal to make last week's fight. That should make putting the rematch together fairly easy.

"Abner just wants to get right back in the ring with this guy," Espinoza said. "You can't judge that fight by one punch. It wasn't even a fight. But Abner came out healthy. It was one punch and it happens to the best in boxing."

The 31-year-old Gonzalez, a noted power puncher from Mexico, dropped Mares (26-1-1, 14 KOs) very hard with a left hook to the chin in the opening round. Mares, 27, a Mexico native from Hawaiian Gardens, Calif., beat the count, but Gonzalez swarmed him and unloaded about an eight-punch flurry -- including another flush left hook -- to drop Mares again, and referee Jack Reiss waved off the fight with five seconds left in the round.

Gonzalez (55-8, 47 KOs), who once employed Mares as a sparring partner in 2006, regained the title he once had and handed Mares, who won world titles in three weight classes over the past 21 months, his first professional defeat.

"The way Abner is, he wants to come back and avenge his loss and prove himself," Espinoza said. "Abner has always wanted to fight the best. After the fight, he called me and said, 'Frank, I want to come back and I want to fight him again this year.' Abner said he's ready to go. He's not afraid to fight anyone. So I said, 'Let's do it,' and I reached out to Richard Schaefer. He said he would work on it for December."

It could be problematic scheduling the fight before the end of the year because it is an unexpected and expensive fight that would need to be added to Showtime's budget. The network, which puts on all of Golden Boy's major fight cards, already has plans for several shows with the promotional company in the fourth quarter and might not be able to afford the rematch until early 2014.

"Richard's going to work on it for December, but if we can't get it done then we may have to wait until January, but my understanding is that December looks good," Espinoza said.

Schaefer said he suggested to Mares that he could take a different (and cheaper) fight before the end of the year, allow Gonzalez to make a defense and then have the rematch next year.

"But Abner was very clear that he wants the fight next," Schaefer said. "I don't know if I can do it this year because it's a pretty big fight and those kind of fights are expensive, but I will work on it and I will talk to Showtime about it."