Manny Pacquiao faces the biggest test of his boxing career on May 2 when he fights undefeated Floyd Mayweather Jr.

That test has been almost six years in the making, and now HBO will chronicle Pacquiao's journey in "Mayweather/Pacquiao: At Last," the network announced Tuesday.

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The one-hour special will premiere on Saturday, April 18 around 11:45 p.m. ET, following HBO's "Boxing After Dark" doubleheader.

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"This is the mega-fight fans have been anticipating for many years, and we are thrilled to chronicle Manny Pacquiao's path to this defining moment in his career," HBO Sports executive producer Rick Bernstein said in a statement. "This special will provide viewers with a narrative of how this fight came to be and spotlight Team Pacquiao's preparations heading into the biggest challenge Manny has confronted in the ring. It will be a terrific primer for any viewer eager to go behind the scenes in the lead-up to May 2."

HBO also announced it will air an "all-new" special on April 25 as part of the lead-up to the fight, plus a mini-marathon of classic Pacquiao fights on April 17.

For many of Pacquiao's previous fights, HBO produced its "24/7" series chronicling each fighter's final few weeks of preparation. But Mayweather is contracted with Showtime, so his participation in this production will consist of archival footage from when Mayweather had a deal with HBO.