Britain's James Guy was dethroned as World champion as China's Sun Yang won his second Gold medal in 48 hours, in the men's 400m freestyle final at the Fina World Aquatics Championships in Budapest.
Sun clocked a time of 1.44.39 to win ahead of American Townley Haas, with Aleksandr Krasnykh of Russia taking the bronze.
Briton Duncan Scott was pipped to a medal by four one-hundredths of a second, with Guy finishing in fifth place.
Double hopes for GB
Guy stood on the blocks at the Duna Arena as defending 200m freestyle World Champion, qualifying fastest from his semi-final in Lane Five, with Sunday's winner from the 400 free Sun Yang in Three and strong American hope Townley Haas in Six.
With Duncan Scott's stunning swim in the second semi however, the Scot lined up next to compatriot Guy in Four, with the two Britons fastest into the final. Hopes were high of a British double-medal haul in the Hungarian capital.
Guy out early
With the 21 year-old from Bury determined to bounce back from disappointment in on Sunday, Guy pushed out to an early lead together with Haas, with Sun lurking in the waves back in fifth.
Scott was being pulled along by the Chinese swimmer, but was happy to bide his time and finish strongly as he did in Monday's semi-final.
Back at the head of the race, Guy was beginning to up the tempo and at the half-way mark turned first, closely followed by Haas.
Sun turns power on
The power of 25 year-old Sun was always to be feared and after springing off the wall, the Hangzhou swimmer began to reel the field in and at the final turn ominously pushed through into the lead, with Guy slipping behind.
Duncan Scott, in the lane below was starting to make his move, with Aleksandr Krasnykh also beginning to enter the medal fray.
With 50m to go, Sun had broken away, but with the scrap for silver and bronze almost a blanket finish.
The American Haas however touched out for second, with Russian Krasnykh's late surge enough for an unlikely medal - fending off Scott, in fourth - with James Guy behind his team-mate.
Despite the double disappointment, two top five finishes for the British men points to a strong medal chance in the 4x200m freestyle relay, which takes place on Friday.