Benson Henderson-Nate Diaz set

Updated: August 15, 2012, 6:17 PM ET
By Franklin McNeil | ESPN.com

UFC lightweight champion Benson Henderson will make the second defense of his title Dec. 8 against Nate Diaz, promotion officials revealed Wednesday.

Former light heavyweight champion Mauricio Rua faces fast-rising Alexander Gustafsson, while Rory MacDonald and B.J. Penn settle their differences in a welterweight match.

USA Today had earlier reported the news on its website.

UFC has yet to officially announce the card or a location for the event, which is expected to air on Fox.

Henderson (17-2) defeated former 155-pound champion Frankie Edgar by split decision in a rematch on Aug. 11 to retain his title.

Diaz, who has competed at 170 pounds, is 3-0 since returning to lightweight. He secured a title shot with a second-round submission May 5 of Jim Miller.

"The Ultimate Fighter 5" winner, Diaz has a professional mixed martial arts record of 16-7.

Penn and MacDonald have been locked in a war of words for several months.

They were originally booked to resolve their dispute Sept. 22 at UFC 152 in Toronto. But the fight was postponed when MacDonald suffered a cut above his right eye during training camp.

More than 30 stitches were necessary to close the wound.

Penn, a former UFC champion at welterweight and lightweight, seriously considered retiring after a lopsided unanimous-decision loss to Nick Diaz on Oct. 29, 2011.

After softening his stance on retirement, the 33-year-old Penn received a challenge from MacDonald and he accepted it.

MacDonald (13-1) is ranked No. 5 among welterweights by ESPN.com. His lone loss, a third-round knockout, came on June 12, 2010, to current interim titleholder Carlos Condit.

Since that setback, MacDonald has reeled off three wins in a row.

Despite registering a fourth-round knockout of Brandon Vera on Aug. 4, Rua failed to land a title shot against the Jon Jones-Dan Henderson winner.

Lyoto Machida was awarded the honor after knocking out Ryan Bader in Round 1 of their fight on the Aug. 4 card.

Henderson will attempt to lift the light heavyweight title belt from Jones on Sept. 1.

Rua (21-6) is itching for another shot at Jones. It was Jones who took the 205-pound belt from Rua, via third-round TKO, in March 2011.

Gustafsson is 14-1. He has won five in a row since losing by submission to fellow light heavyweight contender Phil Davis in April 2010.