Michael Phelps has won his 20th Olympic gold medal after leading from start to finish to claim victory in the men's 200m butterfly.
The legendary American set the pace in Rio de Janeiro but he faced challengers from all areas of the pool as Chad le Clos and Laszlo Cseh both faded down the stretch.
Phelps touched the wall first at each of the first three quarters but he found himself put under pressure by Masato Sakai and Tamas Kenderesi in the final 10 metres.
The 31-year-old seemed to misjudge his reach for the wall but he touched home just four hundredths of a second ahead of Japan's Sakai, with Hungary's Kenderesi claiming the bronze ahead of Le Clos.
Five-time Olympic medallist Cseh could only finish in seventh position, almost three seconds behind Phelps.