Heavyweight contender Cristobal Arreola, who showed off his new slimmed-down physique in a dominant third-round knockout of Nagy Aguilera on Saturday night, is not wasting any time getting back to work.

Arreola, a former title challenger, will return May 27 in Reno, Nev., to headline ESPN2's "Friday Night Fights" in a scheduled 10-round bout against Kendrick Releford, promoter Dan Goossen told ESPN.com on Monday.

The original main event was to have featured junior welterweight Josesito Lopez against Steve Upsher Chambers. However, Lopez suffered a badly bruised knuckle on his left hand and withdrew from the fight.

"As we all know, if there is one thing about Cris that is a constant, he likes to fight," Goossen said. "Josesito injured his knuckle and he and Arreola are in the same camp, both trained by Henry [Ramirez], and with the quick night he had Saturday, the opportunity was there. And, of course, Cris never turns down a fight. He kept that record intact. It's good for everyone. It keeps him busy and keeps him in shape, and the fans in Reno and a national ESPN television audience get to see the new slimmed-down version of Cris."

Arreola (31-2, 27 KOs), 30, of Riverside, Calif., was admittedly not in the best condition in recent fights, skipping training sessions and regularly weighing 250 pounds or more, including for his 10th-round TKO loss to titleholder Vitali Klitschko in 2009 and a majority decision loss to top contender Tomasz Adamek in a significant fight in 2010.

But Arreola took his training for Aguilera seriously and weighed 234 pounds, his lowest since he was 233 for a fight in 2007.

"The key is to keep him active," Ramirez said. "We didn't think it would be two weeks later, but, hey, great. Cris wasn't in a drag out fight with Aguilera. Physically, he feels fine, so let's go right back at it."

Ramirez said he planned to be back in the gym with Arreola later Monday.

"At first when we told Cris about the opportunity he was like, 'Really?' He was a little confused because it was so fast, but when we spoke to him about it and explained what happened, he was like, 'Great, let's do it.' To me this can't hurt. This past training camp was great. He showed up every day -- and you know that wasn't always the case -- and worked his tail off. He decided to stop screwing around and put boxing first, where it needs to be."

Releford (22-14-2, 10 KOs), 29, of Fort Worth, Texas, who has faced several name opponents, is 7-2 in his last nine bouts, although he is coming off an eight-round decision loss to Luis Ortiz in August 2010.

In the ESPN2 co-feature, heavyweights Tony Thompson (35-2, 23 KOs) and Maurice Harris (24-14-2, 10 KOs) square off in a title eliminator that will move the winner one step closer to a mandatory shot against the winner of the July 2 unification bout between Wladimir Klitschko and David Haye.

Dan Rafael is the boxing writer for ESPN.com. Follow him on Twitter @danrafaelespn.