Day 1 of the world swimming championships was day full of world records.

World Swimming Championships - New Records Set On Day 1
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The first day of the swimming competition at the world championships in Rome on Sunday saw a flood of world records, as three of the four gold medals on offer were won in world record time.
German Paul Biedermann and Italian local favourite, Federica Pellegrini respectively won the men's and women's 400-meter freestyle in world record time, while the Dutch women's 4x100m freestyle relay team took nearly two seconds off their own world record.
The other gold medal of the day went to the US 4x100m freestyle relay team, which gave American swimming superstar Michael Phelps a winning start at the championships.
Phelps, who can win six gold medals in Rome, did not swim in the morning heats, but was the first swimmer in the finals.
Phelps, who has won an unprecedented eight gold medals at the Beijing Olympics last year and came to Rome having already won 19 world championship gold medals, touched third in a time of 47.78.
However, the final swimmer for the US, Adrian Nathan, managed to pull past France and Russia on the final leg to give victory to the US in a championship-record time of three minutes, 9.21 seconds.
Russia finished second, while France won the bronze medal.
Phelps said that he regarded winning the relay as the perfect way to end the day. "You realise that you are strong as a team. We wanted to keep the title in the US. We came out, swam our best and we are pretty pleased about it."
Ryan Lochte caused some laughter from his teammates as he said that he felt under pressure going into his swim. "I looked at Alain Bernard. He is about seven feet and all I thought: how do I race against this guy?"
In the women's relay the Dutch team was pushed hard by Germany, for whom opening swimmer Britta Steffen set a 100m world record in a time of 52.22.
Steffen said it was often easier to break world records in a relay. "Sometimes you can swim amazing times because you are a part of a team and that makes a huge difference."
Lying just ahead of Germany on the final turn, Magdalena Veldhuis managed to edge out Daniela Schreiber on the final metres to give the Dutch gold in a time of 3:31.72.
Germany took silver in 3:31.83, while Australia won the bronze medal in 3:33.01.
In the women's 400-meter freestyle, Pellegrini became the first woman to swim under four minutes when she won gold in a time of 3:59.15 seconds, beating Britain's Joanne Jackson and Rebecca Adlington into second and third place.
Jackson finished in 4:00.60, while the Olympic champion Adlington was just. 19 seconds slower.
Pellegrini had previously also held the world record of 4:00.41.
Biedermann, meanwhile, was an unlikely winner in the men's 400m freestyle as he took the gold medal in a race he did not at first want to swim.
The 22-year-old, who said before the heats in the morning that he would scratch from the final if he scraped through with the seventh or eighth-fastest time, set a new European record in the heats and then decided to swim the race.
After only lying fourth at the 100m mark, Biedermann started pushing forward and managed to edge out Tunisian Oussama Mellouli, who won silver two years ago at the worlds in Melbourne.
Biedermann finished in a time of 3:40.07, beating Ian Thorpe's world record from 2002 by one hundredth of a second.
Mellouli won silver, 1.04 seconds off the pace, while the bronze medal went to Chinese swimmer Zhang Lin in a time of 3:41.35.
Biedermann, who had invited his family and girlfriend to Rome to watch him swim, dedicated his victory to his grandmother, who celebrated her 73rd birthday.
"I have to thank them for everything, it is so important that they are here.
"One lives for such moments. I did not even think that I would make the standard for the world championships, let alone the final," he said.
In the first event of the evening, Swedish teenager Sarah Sjostrom broke the world record in the women's 100m butterfly.
The 15-year-old sensation, who had already broken the championship record in the morning heats, managed a 56.44 seconds time in the semi-finals, beating Inge De Brujn's time of 56.61 by. 17 seconds.
In the semi-finals of the women's 200m individual medley American Ariana Kukors took more than one second off Stephanie Rice's world record when she qualified for the finals with a 2:07.03, beating the old record of 2:08.45 by 1.42s.
Rice also comfortably qualified for the finals with the second-fastest time.
The defending champion in the men's 50m butterfly, South African Roeland Schoeman, who set a championship record in the morning heat's with a 22.90, sensationally failed to qualify for the finals as he posted the ninth-fastest time.
He finished in a time of 23.18.