For a second, Sean Gibbons thought he was watching some guy getting ready to fight for a world title.

But Manny Pacquiao had been retired for over a year and it dawned on the American boxing man that his eyes were just playing tricks on him.

Still, what he was seeing inside the gym in General Santos City was not a man who was just there to work out a sweat.

"He was on fire," Gibbons said.

On the receiving end of thunderous blows was Buboy Fernandez, who is helping the former pound-for-pound king rev up for an exhibition fight against DK Yoo on 11 December in Seoul.

It's not a regular fight since it is set for six, two-minute rounds.

But Pacquiao and Fernandez have been training as though the Filipino southpaw's next appearance was a comeback bout.

Gibbons, who arrived from the United States earlier in the week, admits he was surprised to see the intensity of the training session.

You simply can't blame him.

Pacquiao, who turns 44 on 17 December, hasn't fought since getting upset by Cuban Yordenis Ugas in August of last year in Las Vegas.

"Even if it's an exhibition, you just don't get into the ring unprepared," one jaded fight game personality said.

The thing is, Pacquiao's been overdoing it.