Muhammad Ali. Wayne Gretzky. Bo Jackson. Pele. Jackie Robinson. Michael Jordan. All of those names represent some of the greatest athletes in sports history.
But does UFC middleweight champion Anderson Silva belong in the group?
ESPN clearly thinks so, as "The Spider" has been included amongst some high-profile competition in its latest "Greatest Athletes of All Time" poll.
As part of a joint promotion with SportsCenter, ESPN Sport Science will be pairing off 16 sportsmen across major sports and minor sports to determine which man is the best in history from a purely physical, athletic standpoint.
Here's how the brackets are currently set, along with the athletes that will be paired off and when they'll be analyzed for head-to-head comparisons:
• Michael Jordan (NBA) vs. Tiger Woods (Golf)—Feb. 17
• Michael Phelps (Swimming) vs. Anderson Silva (UFC)—Feb. 18
• Muhammad Ali (Boxing) vs. Mark Allen (Triathlete)—Feb. 19
• Bo Jackson (MLB/NFL) vs. Roger Federer (Tennis)—Feb. 20
• Willie Mays (MLB) vs. Jackie Robinson (MLB)—Feb. 21
• Pele (Soccer) vs. Tony Hawk (Skateboarding)—Feb. 22
• Carl Lewis (Track & Field) vs. Wayne Gretzky (NHL)—Feb. 23
• Jim Brown (NFL) vs. Dale Earnhardt Sr. (NASCAR)—Feb. 24
Although fans can vote on the website, the ESPN Sports Science team will be applying its own "unique metrics" based on "speed, strength, durability, reaction time and much more."
If that's the case, this countdown could set itself apart by focusing less on career achievements and more about raw physical gifts. For a mixed martial arts competitor to be included in the list is unusual, but remains a testament to Silva's amazing 17-fight undefeated run in the UFC.