Courtesy of Sherdog.com- Published May 20 2010. What are your thoughts on who the best pound for pound fighters should be? Should your fighter be on this list?

Welcome back, Mr. Rua. We weren’t expecting your arrival, but we do have a spot open for you.

Although the vast majority of the mixed martial arts world believed Mauricio “Shogun” Rua won his UFC title bout with Lyoto Machida in October, Machida remained the favorite when the Brazilian pair met again on May 8 in Montreal. Instead, Rua looked like the man who was MMA’s consensus 2005 fighter of the year as he walloped Machida in less than four minutes, taking the UFC light heavyweight crown, the 205-pound mantle and a spot on this list.

When Sherdog.com began publishing its pound-for-pound rankings in August 2007, Rua appeared as high as No. 2 on the list, due mostly to his outstanding 2005 run during which he trampled four top-10 opponents in little more than six months and won the Pride Fighting Championships 205-pound grand prix. Rua’s résumé isn’t yet that strong again, but he’ll have the chance to climb with a healthy list of potential bouts against well-accomplished fighters: Rashad Evans and respective rematches with Quinton “Rampage” Jackson, Antonio Rogerio Nogueira or Forrest Griffin.

On the topic of sequels, rematches will be formative for these rankings in the coming months. Four entrants on this list are now lined up for return engagements — five, if you include the edged-out Thiago Alves, who falls to the figurative 11th spot with Rua’s re-entry.

1

Anderson Silva UFC middleweight champion Record: 26-4

A month after the fact, the hysteria that surrounded Silva following his dubious domination of Demian Maia in Abu Dhabi has subsided. Attention has now turned to the next fight for the middleweight kingpin, with “The Spider” set to risk his 185-pound mantle in a bout with the outspoken Chael Sonnen at UFC 117 on Aug. 7 in Oakland, Calif. With his recent string of victories over Dan Miller, Yushin Okami and Nate Marquardt, Sonnen has emerged as an accomplished, deserving challenger. But the biggest factor in making this fight a blockbuster will center on Sonnen’s infamous trash talk and whether it can inspire Silva to fight from bell to bell.

2

Georges St. Pierre UFC welterweight champion Record: 20-2

The story remains the same for St. Pierre: Coming off a dominant title performance against Dan Hardy in March, he has been positioned for a rematch with yet another elite welterweight in Josh Koscheck, courtesy of the former NCAA national wrestling champion’s May 8 win over Paul Daley. St. Pierre and Koscheck met previously in August 2007, with St. Pierre winning a unanimous decision. Now, when they collide three-plus years later, it will be on the heels of Season 12 of “The Ultimate Fighter,” which figures to build the second GSP-Koscheck bout with an easy and obvious face-heel dynamic.

3

Fedor Emelianenko Strikeforce heavyweight Record: 31-1, 1 NC

The good news: Emelianenko’s Strikeforce contract has, at least for now, been ameliorated, allowing “The Last Emperor” to meet Fabricio Werdum on June 26 as the promotion returns to San Jose, Calif. The bad news: Many MMA observers have grown skeptical of Emelianenko’s run of opponents, and following Alistair Overeem‘s May 15 destruction of Brett Rogers, Werdum appears far from the most appealing non-UFC heavyweight opponent for Emelianenko. A showdown with “The Demolition Man” has quickly become the premier fight for Emelianenko heading into the second half of 2010.

4

Jose Aldo WEC featherweight champion Record: 17-1

Aldo entered his April 24 showdown with Urijah Faber as the favorite, but many expected “The California Kid” to at least present the Brazilian dynamo with a real test. Instead, Aldo crushed and demoralized Faber in front of his fans in Sacramento, Calif. For five lopsided rounds, Aldo smashed Faber with low kicks, hobbling him into helplessness inside the cage. With the victory, Aldo appears all but untouchable in the featherweight division, despite only two outstanding wins — Mike Thomas Brown and Faber — on his docket. With the perception of his dominance reinforced, Aldo figures to be a considerable favorite over his likely next challenger, Manny Gamburyan, whenever they meet later this year.

5

Jon Fitch UFC welterweight Record: 22-3, 1 NC

With a straightforward and prosaic fighting style, Fitch doesn’t appear to be as close to another crack at the UFC welterweight title as he would like to be. However, the former Purdue wrestling captain still boasts a staggering 12-1 record in UFC competition, having compiled it in one of MMA’s strongest divisions. Unfortunately, Fitch’s rematch with Thiago Alves has been canceled twice already, and the third iteration of the bout was hit with another delay. Zuffa officials pushed the date back from UFC 115 on June 12 to UFC 117 on Aug. 7 to ensure Alves’ full health. Let’s hope it happens this time. Holding the title of the undisputed second banana at 170 pounds remains a great MMA accomplishment.

6

Frankie Edgar UFC lightweight Record: 12-1

At UFC 112 in Abu Dhabi, Edgar scored one of the most significant wins of 2010, dethroning lightweight kingpin B.J. Penn and taking the UFC 155-pound title. Although it wasn’t exactly a popular decision, Edgar took all three judges’ scorecards behind his aggressive combination punching and stellar movement. But the surprise champion will have to replicate the feat in order to earn unanimous consideration as the sport’s top lightweight, as he has signed on for an August rematch with Penn in Boston.

7

B.J. Penn UFC lightweight Record: 15-6-1

Moving from one controversy to another, Penn lost his UFC lightweight title and MMA’s 155-pound mantle on April 12 in a shocking upset by Frankie Edgar. While debate still rages over the legitimacy of the bout’s outcome, Penn has begun a book tour to promote his eye-opening biography. In particular, the book has drawn the ire of UFC president Dana White over its anecdotes on the Hawaiian’s past dealings with the company. Brouhahas notwithstanding, “The Prodigy” will get his chance at redemption — and the opportunity to regain top status at 155 pounds — in August, when he meets Edgar for a second time at UFC 118 in Boston.

8

Mauricio Rua UFC light heavyweight champion Record: 19-4

With questions swirling about what would happen if his rematch with Lyoto Machida went to the judges, Rua made sure the script played out differently than their controversial first bout, clobbering “The Dragon” less than four minutes into their May 8 meeting. Rua lacks the cachet he carried in 2005, when he tore through four top-10 opponents in half a year. But with a forthcoming title eliminator between Quinton “Rampage” Jackson and Rashad Evans and the UFC’s strong grip on elite 205-pound talent, Rua will have the opportunity to carve out a brilliant hit list in a strong division — the backbone of any pound-for-pound résumé.

9

Jake Shields Strikeforce middleweight champion Record: 25-4-1

There was a time just a few short years ago when Shields was reviled for being one of MMA’s most loathsome fighters to watch. But during the past five years, the Cesar Gracie protégé has transformed himself from a drab, peripheral contender to one of the sport’s elite fighters. With his dominant April 17 upset of Dan Henderson, the Strikeforce middleweight champion now boasts a 14-bout winning streak and top-five credentials in two separate divisions. The serious question surrounding Shields now centers on whether he will remain a Strikeforce commodity or choose a future in the Octagon against a deeper roster of competition.

10

Lyoto Machida UFC light heavyweight Record: 16-1

10. Lyoto Machida (16-1) The majority of the MMA world believed that Mauricio “Shogun” Rua was the better man in his first meeting against Machida in October. In their May 8 rematch, Machida certainly appeared to be the lesser man. The Belem, Brazil, native was polished off in less than four minutes — a far cry from the supposedly untouchable fighter who took the title from Rashad Evans just a year earlier. However, criticisms at this point seem too sharp. Lost in the postfight absolutes was the fact that it was not that long ago that Machida blew away strong competition in a deep division, crushing both Evans and Thiago Silva in his 2009 campaign. With the entry of Mauricio Rua, previously 10th-ranked Thiago Alves falls outside Sherdog’s pound-for-pound top 10.