Eleven-time world surfing champion Kelly Slater will be out for up to six months after breaking his foot in the J-Bay Open in South Africa.
The 45-year-old American was taken from the water at Jeffreys Bay and rushed to hospital after he was struck by his board prior to his second-round heat.
Slater said the incident was "like smashing my foot with a big hammer".
Writing on Instagram, he said he is likely to need between four and six months to recover.
In an earlier post, which included an X-ray of his foot, he wrote: "You ever folded your entire foot backwards? If you try it sometime, this is what it might look like.
"Sorta feels like I'm giving birth out of my foot right now.
"It sucks but so many people deal with such horrible things around this world every day that a broken foot is pretty minor in the scheme of things. Sometimes a bad thing is a good thing."
Meanwhile, Australia's Mick Fanning and Brazilian Gabriel Medina were pulled from the water in Jeffreys Bay after a shark was spotted swimming into the competition zone.
Fanning, 36, escaped a shark attack while competing in the same event two years ago.
Surfing is one of five new sports confirmed for the 2020 Tokyo Olympic Games.