Pacquiao, who Fortune said had been initially stubborn to change his ways, acknowledged that the new training regime had paid off.
But in his Facebook account, Donaire said he was replaced in the last minute.
When asked what was next for him, Pacquiao said, "I want to defend my title and give a good show in the ring". But unfortunately I'm not able to work in his corner 'coz someone took my spot.
The 35-year-old Argentine, who came in with a reputation as a big puncher, had no answer to Pacquiao's blistering speed and he dropped again in the fifth.
Pacquiao's expected cornermen are Boboy Fernandez and his conditioning trainer Justin Fortune.
Pacquiao is going for his 60th victory since turning pro in 1995, but despite winning 38 of his first 47 fights by knockout, he has not stopped an opponent in nine years. We weren't pushing hard like when we were young.
Aside from the world title fights involving the two Filipinos, there will be two more world championships in the Fight of Champions fight card.
"Firstly I'd like to thank them both for being in the stands to witness my fight", the 39-year-old Pacquiao told a news conference later, referring to both Dr Mahathir and Duterte.
"He's a great fighter. I lost to a great legend". "You win some, you lose some", Matthysse said.
Pacquiao was also excited that he managed to exchange a few words with Dr Mahathir after his fight.
"Right now, I'm happy to go back to my country and celebrate the victory".
Lu Bin's fearless bid for a record world title win in just his second professional fight came crashing to earth when he was knocked out in the dying seconds of his battle with experienced WBA light flyweight champion Carlos Canizales of Venezuela.
First fight is early at 7 in the morning while the main event is expected to be beamed worldwide at 11 am Kuala Lumpur time. South African Moruti Mthalane won a close twelve round unanimous decision over Pakistan's Muhammad Waseem to capture the IBF flyweight title.