Hawaiian mixed martial arts superstar BJ Penn will return to the UFC at a new weight and coach opposite former UFC lightweight champion Frankie Edgar in the 19th season of The Ultimate Fighter.

Penn, who looked to have retired from the sport after his defeats to Nick Diaz and Rory MacDonald at welterweight, contacted UFC president Dana White and asked to fight deposed UFC lightweight champion Benson Henderson before taking on Edgar for the third time.

But with Edgar already slated to coach in the UFC's tournament-based reality show and unwilling to drop to bantamweight to coach against Urijah Faber, White opted to swap Penn for Faber and set up a featherweight coaching battle.

Penn has never fought as a featherweight (135lbs) but is a former UFC world champion at welterweight (170lbs) and lightweight (155lbs).

Now he wants to make a run at the featherweight title, currently held by pound-for-pound star Jose Aldo.

UFC president Dana White told US-based UFC news show UFC Tonight: "When BJ Penn gets fired up about something he goes crazy.

"The kid's fired up [and] he's got me fired up about this.

"He believes he can beat Frankie Edgar [and] he can compete at 145 pounds.  It's tough to say no to BJ."

White revealed Penn's comeback call came out of the blue - and was perfectly timed as it came shortly after the first-choice TUF pairing of Edgar and Urijah Faber couldn't come to an agreement over a weight class for a bout.

"It was going to be Urijah Faber and Frankie Edgar," explained the UFC president.

"Faber is 135 pounds, Edgar is at 145.  Edgar didn't want to go to '35 Urijah wasn't crazy about going to '45."

With the two pushing for a catchweight bout, White received communication from Penn about coming back to the UFC, and everything fell into place after that, with Penn taking the coaching slot alongside Edgar.

The duo will coach opposing teams of light-heavyweight and middleweight fighters, who will compete in single elimination tournaments, with the prize of a six-figure contract on offer for the winner of each weight division's competition.  The series will be filmed in the first quarter of 2014, with the show set to be aired in April.

The pair have met twice before - at lightweight - with Edgar taking decision victories in both encounters.

OCTO-FACTS: BJ PENN

  1. Penn is known to all and sundry as BJ Penn, with the initials standing for 'Baby Jay', but his real name is Jay Dee Penn
  2. He is only the second man to win UFC world titles in two different weight divisions (welterweight and lightweight)
  3. He is the only fighter to claim a stoppage win in all five rounds
  4. He is a former Brazilian Jiu Jitsu world champion in the 154-pound "Pena" division - the first non-Brazilian fighter to win a Brazilian Jiu Jitsu world title
  5. His upcoming bout against Edgar will represent his fifth different weight class, having already competed at lightweight (155lbs), welterweight (170lbs), middleweight (185lbs) and light heavyweight (205lbs)
  6. He also fought Lyoto Machida (who would later go on to become the UFC light-heavyweight champion) in an open-weight bout where Machida weighed more than 220lbs
  7. UFC middleweight superstar Anderson Silva once said Penn was the greatest mixed martial artist in the history of the sport
  8. His opposite number in the upcoming season of The Ultimate Fighter, Frankie Edgar, described Penn as '...the greatest lightweight ever'