Americans Michael Phelps and Brendan Hansen broke their own world records and South Korean youngster Tae Hwan Park won his second gold medal on the last day of the Pan Pacific Championships on Sunday.

Phelps won his fifth gold of the competition in the 200 metres individual medley, holding off team mate Ryan Lochte in a time of 1:55.84 to beat his previous mark of 1:55.94 set three years ago.

Hansen lowered his record in the 200 metres breaststroke, winning the event in 2:08.50 to eclipse his previous time of 2:08.74.

"Ryan and I both decided we were just going to take the butterfly out and go for it," Phelps told reporters. "When we get in the water to race, we bring out the best in both of us."

Lochte finished 0.27 seconds behind Phelps despite holding a slim lead through 150 metres.

Hansen captured the evening's other world record.

"My race was to take it out a bit slower than I did at the national, but it was hard to hold back," Hansen said. "I knew if I swam the race right I would have a lot left in the tank."

Park, who won the men's 400 metres freestyle on Saturday, his country's first gold medal in a major international meet, powered past American Erik Vendt in the final 50 metres of the 1500m freestyle to win his second gold. He also took silver in the 800m.