Lightweight

1. B.J. Penn (Pictures) (13-4-1)
His return to the division led many to proclaim Penn as the world's best lightweight. With his dominant victory to retain the lightweight championship against Sean Sherk (Pictures) at UFC 84, Penn validated those claims. With a Roger Huerta (Pictures)-Kenny Florian (Pictures) eliminator on tap for August and his desire to rematch Georges St. Pierre (Pictures) made vocal, Penn's future should certainly prove exciting.

2. Takanori Gomi (Pictures) (28-3-0, 1 NC)
Gomi will return to action on the next Sengoku bill on Aug. 24 against a yet-to-be-determined opponent. More importantly, the card will also feature an eight-man lightweight tournament that includes Eiji Mitsuoka (Pictures), Satoru Kitaoka (Pictures), Kazunori Yokota (Pictures), Rodrigo Damm (Pictures) and Duane Ludwig (Pictures). The eventual winner will likely go on to challenge Gomi for the vacant Sengoku lightweight championship.

3. Eddie Alvarez (Pictures) (15-1-0)
It was the best of times, and it was the worst of times for Alvarez. In the biggest bout of his career, the Philadelphian came through with a fight of the year candidate against perennial top lightweight Tatsuya Kawajiri (Pictures) on July 21, as he became the first man to knock out the "Crusher." However, the enormity of the moment was stifled when Alvarez could not advance to the tournament final to meet Shinya Aoki (Pictures) because of a badly mangled right eye he sustained in his brawl with Kawajiri. No matter what comes next for Alvarez -- a second crack at a bout with Aoki or a rematch with newly crowned Dream champion Joachim Hansen (Pictures) -- the once-prized prospect has arrived as a top fighter and breaks into these rankings at number three.

4. Joachim Hansen (Pictures) (19-7-1)
With losses to the likes of Shinya Aoki (Pictures), Eiji Mitsuoka (Pictures) and Eddie Alvarez (Pictures), it seemed that the Norwegian nightmare's days as a top lightweight may have been finished. However, when the stars lined up and gave "Hellboy" his chance to step back into the Dream lightweight grand prix after he easily handled Kultar Gill (Pictures) in the reserve match, Hansen blasted Aoki to gain a measure of vengeance, the Dream lightweight championship and his biggest win in years.

5. Shinya Aoki (Pictures) (17-3, 1 NC)
Overcoming Gesias Cavalcante (Pictures) in April affirmed Aoki's place as a top lightweight and one of the favorites to win the Dream tournament. With his dominant win over Caol Uno (Pictures) and Eddie Alvarez (Pictures) unable to continue into the final, it seemed inevitable Aoki would win the tournament, facing Joachim Hansen (Pictures), a man out of whom he had already made a highlight reel with his New Year's Eve gogoplata in 2006. However, this time around, Aoki's rubber guard wizardry was no match for Hansen's ferocity, as the Norwegian smashed Aoki to claim the tournament. While emotional outpouring in defeat may garner some sympathy, Aoki's loss to Hansen sees him fall from third to fifth in these rankings.

6. Gesias Cavalcante (Pictures) (14-2-1, 1 NC)
Calvacante came out on the losing end of things in his April 29 rematch with Shinya Aoki (Pictures). Now, "JZ" is looking at three to four months on the shelf to recover from a torn anterior-cruciate ligament. As he sits on the sidelines, the ascent of Alvarez and Hansen forces Cavalcante from fourth to sixth in the Sherdog.com rankings.

7. Josh Thomson (Pictures) (15-2-0, 1 NC)
Long critical of his perceived place in MMA rankings, Thomson went out and put on the best showing of his career, as he dominated Gilbert Melendez (Pictures) wire to wire in their June 27 bout for the Strikeforce lightweight championship. Always considered a supremely talented fighter, Thomson finally has a performance to match. However, due to the Dream tournament outcomes, Thomson is nudged down from fifth to seventh.

8. Gilbert Melendez (Pictures) (14-2-0)
A favorite going into his June 27 title defense against Josh Thomson (Pictures), Melendez was completely outclassed over five rounds and lost a lopsided decision. What's next for the talented Cesar Gracie (Pictures) prospect is uncertain, and for now, Melendez falls from sixth to eighth in the 155-pound pecking order.

9. Tatsuya Kawajiri (Pictures) (22-5-2)
Not unlike his September 2005 mega-clash with Takanori Gomi (Pictures), Kawajiri threw caution to the wind and fought fire with fire against Eddie Alvarez (Pictures). While it may eventually earn him fight of the year honors, it did not earn him a victory, as Alvarez rallied back from adversity to stop Kawajiri on strikes for the first time in his career. In need of a major win, Kawajiri slides from seventh to ninth with the loss, just his second in nine fights.

10. Sean Sherk (Pictures) (32-3-1)
Sherk’s 10 months of torture were punctuated in painful fashion, as B.J. Penn (Pictures) manhandled him in their lightweight title clash in May. However, the possibilities are numerous for Sherk, who has only fought thrice in the division, making plenty of matchups with the UFC's young, talented lightweights possible. Until then, the "Muscle Shark" skids form eighth to 10th in the Sherdog.com rankings.

* Formerly ninth-ranked Caol Uno (Pictures) and 10th-ranked Mitsuhiro Ishida (Pictures) both fall outside the top 10 with the entry of Eddie Alvarez (Pictures) and the re-entry of Joachim Hansen (Pictures) following their Dream lightweight grand prix successes on July 21.