These two bears clearly woke up in a grizzly mood as they trade blows during a heavyweight bout.
A rare blond grizzly bear had challenged his brown adversary to a play fight on an icy tidal flat.
The two hulking bears, which stand 8ft tall on their hind legs, take a firm grip before wrestling each other to the floor.
Photographer Steven Kazlowski, 40, captured the bears on the Alaskan Peninsula, in Katmai National Park, U.S.
Katmai holds what are believed to be some of the world's largest grizzy bears due to the huge number of returning salmon, which swim upstream to spawn.
North American grizzlies are usually dark brown, but can very occasionally be a much lighter colour.
Mr Kazlowski, from Seattle, said spotting the blond bear was 'very special'
Take that: The brown bear takes a playful swipe at his lighter coloured adversary as they clash on the shore
Heavyweight: The brown bears rear up to their full heights as they lock paws around each other
He said: 'We had heard about the blond bear when we were in another bay and headed north to find it.
'They are extremely rare and I had never heard of one before.
'This was a game that was friendly, but could always turn to a fight if things got out of hand.
'We watched them close up for hours playing till the sun set.
'When we first saw them they were fishing and they went back to it several hours after they were done playing.
Give us a hug: The two bears mock bite each other as their play fight continues
Cuddly: As the two adults continue to wrestle they begin to lose their footing on the rocky shore
'There were many more bears around but they were all spread out over several miles.
'I was within 50ft at one point. But when they were playing I gave them lots of room as I did not want them to move off or stop playing.'
He added: 'This was rare and very special because they were playing in perfect afternoon light in a great place.
'And to have such a rare animal as this white grizzly is something that will happen again no time soon.
Brown bears, which are found mainly in Russia, the U.S. and Canada, can weigh up to 70 stone.
They eat berries, roots, sprouts and fungi, as well as fish, insects and small mammals
Brief paws: The two bears wrestle each other to the ground after several minutes of trying to get the better of their adversary
He's a teddy bear really: The rare blond bear moves away after the playfight to go fishing for salmon
source: dailymail