Abul Hossain Gazi from Bangladesh's Khulna district had accompanied his son and six others fishing in the Sunderbans yesterday, the largest mangrove site in the world.
His son Monju Gazi was collecting firewood when he was attacked by a Royal Bengal tiger.
Mr Hossain rushed to his aid and the two wrestled the beast for half an hour before other fishermen arrived, and succeeded in beating it back into the undergrowth.
Mr Gazi, 30, was taken to a nearby health centre with serious injuries to his head, chest, hands and legs.
Although the number of attacks by man-eating tigers has fallen from more than 40 annually a couple of decades ago to less than 10 a few years ago, the problem has not been solved completely.
Most of the mangroves are in Bangladesh, but neighbouring India is not free of the menace either.
Governments on both sides of the border have regulated the movement of people inside the Sunderbans, which is also a world heritage site. However, the human-tiger conflict still persists.
Bibhab Talukdar of the National Board for Wildlife in India told the Press Association: "Villagers have been using masks for decades now, and it has helped curb the problem a little."
"The tigers usually attack from behind. By wearing a mask, villagers can trick the animals into thinking they are watching. It seems to have worked quite well.
"But the authorities must find out the specifics of incidents like these - whether the people involved were wearing masks, whether they got too close to the tiger, etc," he added.
Tigers usually turn to man-eating when they are too old to catch wild prey and humans become an easy target.