The multi-time Trainer of the Year sees the eight-weight world champion taking a huge risk with his reputation by taking on a lesser-known fighter in Australian contender Horn.
On the one hand, a possible second fight with the returning Floyd Mayweather is on the radar with an impressive display, whilst on the flipside, a loss could mean devastation for Pacquiao’s career.
“Manny is in a must-win situation. He wants a rematch with Mayweather,” Roach said to gathered media in Brisbane.
“With Mayweather, you have to look good against an opponent, you have to be impressive.”
He added honestly: “If he struggles in this fight, it could be over. Depending on how he lost, I would probably encourage him to retire.”
Despite the potential for disaster, Roach is confident Pacquiao will prove his class once again and then move on to open talks with the winner of Mayweather v Conor McGregor after the summer.
“I expect Manny’s best in this fight. I am looking for a big win here as we want to go on to bigger and better things,” outlined Roach.
It’s unclear whether Mayweather will continue his career on the back of a McGregor triumph as nobody can ever second guess with the ‘Money’ man will do next.
Gaining a nine-figure check for beating McGregor would mean either certain retirement for an option-less Mayweather, or the reviving of a rematch with Pacquiao in a bid to top his earnings from their first meeting in 2015.