Scientists tried to measure the punching power of boxing world champion Ricky Hatton - but The Hitman's near half-ton punch broke the equipment.
Sensors in the bag broke at the first attempt
Researchers initially thought Hatton was packing a right-hand with 1,500kg (3,307lb) of force behind it.
But a re-analysis of the data found the figure was about 400kg (882lb) - still 10 times that of an average person.
"The level of force he generated was quite astonishing," said Dr Qingming Li of the University of Manchester team.
Hatton's fastest effort was clocked in at 32mph (51km/h) - a left hook that he has used to floor 30 of his 42 opponents.
His average punching speed was measured out at 25mph (40km/h) - giving opponents less than one tenth of a second to move out of the way.
The results show the power and speed that await Hatton's next opponent, Jose Castillo, in their IBO light welterweight clash in Las Vegas on Saturday.
Hatton, 28, from Hattersley, Greater Manchester, said: "It was great working with the experts and the technology, and for me it was really interesting to see just how fast and hard I can hit.
"It was my first visit to the University of Manchester and I was impressed with the facilities there."
The Hitman was put through his paces by a team of impact engineers from the university's School of Mechanical, Aerospace and Civil Engineering (MACE).
Hatton interrupted his training schedule to take part
Dr Li worked with biomechanics equipment specialist Biosense Medical Ltd to gauge the strength and speed of Hatton's best shots.
Sensors attached to a 30kg (66lb) Lonsdale punch bag wired up to a laptop containing software to measure and analyse the data.
Hatton was asked to step up and pound the bag - and the force caused an initial malfunction in the sensor.
Engineers used alternative data and looked at previous studies to prove that Hatton hit the target with an instantaneous force of 400kg (882lb) - approaching half a US ton.
A US ton - or short ton - equals 2,000lb (907.19kg).
Measuring the forces applied in football studies, the team also worked out that Hatton's average punching force is more than twice the kicking force of a Premier League footballer.
Dr Li added: "It was certainly a very different project from the type we usually work on, but it does demonstrate the expertise and versatility we have within the department."