When the world’s most famous boxer chose Joshua Clottey, a New York welterweight, for this Saturday’s championship bout in Texas, Manny Pacquiao wasn’t just plucking a relative unknown out of obscurity — he was elevating a Bronx gym.

“This is the biggest fight out there right now in boxing, period,” said Gjin Gjini, the owner of Clottey’s stomping grounds, John’s Boxing Gym.

Since its founding 30 years ago, John’s Gym, on Westchester Avenue in Melrose, has seen its share of quality boxers — but few have gotten a shot to become world champ.

Not that many people outside the Bronx give Clottey much of a chance against his foe. But many of the gym’s trainers believe the Ghanaian native can help bring Bronx boxing back to its glory days.

“It’s a big deal. It’s great for Clottey, it’s great for the gym, and especially the young kids coming up, looking forward to a championship,” said Richard Jenkins, 64, a trainer at the gym for 16 years. “Just the other day, someone comes in and says, ‘Well how many champs you got here?’ and you just point up at the wall and there’s Josh Clottey. It’s really a big deal if the gym has a champ.”

Clottey, who is ranked fifth in the welterweight class (between 140 and 147 pounds), was an unlikely choice to fight the man whom Ring magazine ranks the No. 1 “pound for pound” boxer in the world.

But after a disagreement over the terms of pre-match drug testing led Pacquiao to call off his much anticipated fight with No. 2-ranked Floyd Mayweather Jr., Pacquiao was left scrambling to find a replacement.

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While the betting odds are against Clottey, some at John’s Gym predicted the fighter could go the distance.

“For us, who are here, this means a lot. It’s like a family,” said Gjini.