After nine days of action in the 12th FINA World Championships, the swimming events at the Susie O'Neill pool, the temporary pool constructed inside Melbourne's Rod Laver Arena, known worldwide as the home of tennis's Australian Open, have commenced with four finals decided on the opening night.

South Korea claimed their first ever World Championship gold after a sterling come-from-behind win from promising young star Park Tae Hwan in the mens 400m freestyle. Park, who was fourth at the final turn and seemingly out of the equation, swam a magnificent final 50-metres to power past Tunisia's Oussama Mellouli and Australian world champion Grant Hackett in the final metres to claim the gold in 3:44.30, 0.72 seconds, ahead of Mellouli, with Hackett winning the bronze from lane eight.

In the women's 400m freestyle, Frenchwoman Loure Manaudou continued her recent dominance of the event cruising to the title in a time of 4:02.61, less than half a second outside of her own world record from last year. Manaudou looked set to post a new world benchmark after a blistering first 200-metres and was never headed throughout the race, but started to fade slightly in the final 150-metres. Poland's Otylia Jedrzejczak completed a remarkable return from a serious car accident last year to claim silver, less than two seconds behind Manaudou, with Japan's Ai Shibata winning the bronze.

The most anticipated race of the night was the women's 4x100m freestyle relay featuring the three fastest sides  in the events history - Germany, United States and Australia. The home nation regained the supremacy of the event thanks to a brilliant final leg from Jodie Henry. Conceding close to a body length at the beginning of her leg she proved to be far too powerful for the American Kara Lynn Joyce as the Aussies set a new championship record of 3:35.58, pipping the US by only 0.10 of a second, with the Netherlands snapping at the heels of the big two teams to finish third.

The race had been a titanic struggle between the two rivals from the opening buzzer, Libby Lenton set a new personal best to give the Aussies an edge over Natalie Coughlin, while the the American middle legs of Lacey Nymeyer and Amanda Weir did well to not catch the Australians but to also set up what should have been a race-winning lead by the final change.

The big disappoint of the night was the performance of the Germans who were never in the hunt, eventually finishing in fourth after Britta Steffen swam the fastest leg of the race in 52.65. None of her teammates managed a time under 54 and half seconds.