MMA's 10 best pound-for-pound fighters

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.