This fighter grappled to a draw with former UFC two division champion “The Natural” Randy Couture (16-8) in a 2006 submission grappling contest and has only lost to fifth-ranked “Dreamcatcher” Gegard Mousasi (23-2-1) in MMA since 2003.

Souza’s climb up the ranks, second-ranked Jake Shields‘s (24-4-1) hold on the top contender spot, and Strikeforce’s signing of third-ranked “Hollywood” Dan Henderson (25-7) gives Strikeforce four fighters in the 185-pound top ten.  (Of course, Mousasi has abandoned the division to take the Strikeforce 205-pound title.)

It’s likely Shields and Hendo’ will settle the top contender spot and fight for Strikeforce’s title in April, with the winner legitimately claiming the rank of best matchup for Fighters.com and UFC Middleweight Champion “Spider” Anderson Silva (25-4).

Silva will fight tenth-ranked “Phenom” Vitor Belfort (18-8) at UFC 109 in Las Vegas February 6.  Belfort can’t be overlooked at 185 pounds with Silva coming off of elbow surgery and five months hiatus.

Fourth-ranked “Great” Nate Marquardt (29-8-2) and seventh-ranked Chael Sonnen (23-10-1) will battle the same night for the next title shot.

And sixth-ranked Demian Maia (10-1) will test strong prospect Dan Miller (11-2), making a trio of UFC 109 fights with maximum impact on the division rankings.

Also in December, ninth-ranked “Ely” Paulo Filho (16-1) submitted Tatsuhiko Nishizaka (3-5-1) at Bitetti Combat 5 in São Paulo December 12.  If Filho can get his act together, Fighters.com wouldn’t be surprised to see him in Strikeforce soon.

Fighters.com’s December Middleweight Rankings

1. “Spider” Anderson Silva (25-4)

2. Jake Shields (24-4-1)

3. “Hollywood” Dan Henderson (25-7)

4. “Great” Nate Marquardt (29-8-2)

5. “Dreamcatcher” Gegard Mousasi (23-2-1)

6. Demian Maia (10-1)

7. Chael Sonnen (23-10-1)

8. “Jacare” Ronaldo Souza (9-2)

9. “Ely” Paulo Filho (16-1)

10. “Phenom” Vitor Belfort (18-8)

In his second consecutive fight for Bitetty Combat, Filho submitted Tatsuhiko Nishizaka (3-5-1) in 3:00 of round one in the main event.

Filho is the former WEC middleweight champion and has challenged Strikeforce light heavyweight champion Gegard Mousasi (23-2-1).  But, Filho recently bailed on a scheduled fight at DREAM 12 in Osaka October 25 and Strikeforce has shown no public interest in signing Filho and making the fight.

Rua TKO’d Golden Glory’s Jason Jones (3-9-1) at 3:20 of round two in a light heavyweight fight.  Rua hinted that he might continue to fight at 205-pounds.