Josh Thomson vs. Gilbert Melendez title fight headlines "Strikeforce: Evolution" on Dec. 19

A lightweight title-unification bout between Strikeforce champion Josh Thomson (16-2) and interim champion Gilbert Melendez (16-2) headlines the organization's Dec. 19 event, MMAjunkie.com (UFC blog for UFC news, UFC rumors, fighter interviews and event previews/recaps | MMAjunkie.com) has confirmed.

The five-round rematch from the duo's original June 2008 meeting takes place at the HP Pavilion in San Jose, Calif., and tops the Showtime-televised portion of the event.

Thomson pulled off the upset and won the original meeting via lopsided unanimous decision but hasn't fought since a non-title fight over Ashe Bowman in September 2008.

A source close to the event told MMAjunkie.com over the weekend that Bellator Fighting Championships lightweight champion Eddie Alvarez, at least briefly, was under consideration for the card, possibly as Melendez's opponent. Strikeforce has a partnership with the Japanese-based DREAM organization, which also has a contract with Alvarez. Bellator is looking for its champions to get fights in outside promotions while it gears up for a second season, which will determine No. 1 contenders for each weight class.

The Thomson vs. Melendez rematch long has been on Strikeforce's calendar since Thomson took the original meeting with 50-45 scores on all three judges' cards. An April 11 booking was scrapped after Thomson suffered an ankle injury during training. A booking for the Aug. 15 "Strikeforce: Carano vs. Cyborg" event also was scrapped when Thomson wasn't medically cleared because of lingering injuries. In fact, Strikeforce officials weren't immediately confident Thomson would be ready to go for the December date, as well.

Now, finally set, Thomson returns from a 15-month layoff and enters the fight with an eight-fight win streak. The UFC and PRIDE veteran has defeated the likes of Rob McCullough, Hermes Franca, Duane Ludwig and Name Phan during his nine-year career, though the original Melendez victory arguably was the biggest of his career.

Melendez, meanwhile, is 2-0 since his loss to Thomson last year. He topped Rodrigo Damm in April for the organization's interim title and then scored a third-round TKO (and avenged his first career loss) by defeating Mitsuhiro Ishida in his first interim-title defense. The longtime Strikeforce fighter and PRIDE veteran opened his career with 13 straight victories but went 1-2 in 2008. He now looks for his third straight victory.

The latest "Strikeforce: Evolution" card now includes:

* Champ Josh Thomson vs. interim champ Gilbert Melendez (lightweight title-unification bout)
* Cung Le vs. Scott Smith
* Matt Lindland vs. Ronald "Jacare" Souza
* Muhammed "King Mo" Lawal vs. Mike Whitehead*
* Robbie Lawler vs. TBA
* Antwain Britt vs. Scott Lighty*

* - Not yet officially announced