Yuhan clocked in at 4:07.72, touching 5 seconds ahead of anyone else in the field.
The veteran distance swimmer dominated the men’s 400 freestyle with a time of 3:42.70.
Canada’s Taylor Ruck broke her own meet record and moved to within a tenth of the junior world record in finals of the 100 free, then helped Canada win gold in the mixed 4×100 free relay.
World Junior Recordholder Anton Chupkov of Russia is seeded first in the men’s 100m breaststroke on Day 1 of the 5th FINA World Junior Swimming Championships 2015 in Singapore.
Taylor Abbott, from Nitro Swimming in Austin, became the first American to ever win World Junior Open Water gold on Saturday.