Originally, the plan for Ben Henderson was, to headline the The Ultimate Fighter 21 Finale in July against Michael Johnson. Two weeks ago, however, the former UFC lightweight champion pulled out of the bout due to undisclosed reasons. On the latest episode of Ariel Helwani's The MMA Hour, Henderson now revealed:

"I had an injury. I won't be cleared for a little while, so I had to respectfully bow out of that one. I was kind of disappointed in myself, but you've got do what the doctors say because ultimately they have the piece of paper they have to sign off for you, and my doctor wouldn't do that. So I'm not cleared."

He said this injury has been "the hardest thing he ever had to deal with", although he didn't go into details what kind of injury it was. Johnson told MMA Junkie last week, that Henderson suffered from a detached retina, sustained during training. "Bendo" didn't want to confirm that, and only hinted that "it was in that area", but that he "probably won't ever say exactly what it is".

Related: Ben Henderson and Michael Johnson beefing on twitter after cancelled bout.

Henderson just snapped a two-fight losing streak to now-champion Rafael dos Anjos and now-number-one contender Donald Cerrone with a submission win over Brandon Thatch, in his welterweight debut in February. What originally was thought to be a one-time affair, could now become the new home for the former 155-pound kingpin.

"I think we decided, my coach and I, John Crouch, to go up to 170. We're going to take the time off to rebuild my body. We're going to do a whole new unveiling for 170. I'm trying to walk around at 182 to 185, walk around at maybe six- or five-percent body fat, and just be explosive. Really open some eyes up with my next fight at 170."

As of right now, there is no information on how long Henderson will be sidelined by his injury, but he promised to be back by November 28, when the UFC hits South Korea's capital Seoul for the first time ever.

"I'll do whatever it is I physically, possibly can," Henderson said. "I will be ready for that Korea card. And you're going to see a whole new beast."

You can watch the whole segment above. (Transcription via MMA Fighting)