5 Seconds Of Summer'sself-titled album has debuted at No. 1 on the Billboard 200 with more than 253,000copies sold in its first week.

The long-awaited release is the biggest debut by an Australian artist ever in the Soundscan era – and actually beats their own She Looks So Perfect EP, which shifted a cool143,000 copies in April.

The achievement means that their LP has also become the biggest new artist debut of 2014.

Having already reached No.1 globally on iTunes in 76 countries, this full-length has sold more than 1.5 million units worldwide, while total single track sales in the U.S. have surpassed two million.

Here in the UK -5SOS also announce the release of their third single Amnesiaon September 7.

[related]The tuneis a change in pace for the pop-rock group, with Luke saying of the track: "The song has so much meaning and it is one of the most heartfelt songs on the album and is really special to us as a band.”

The lads also revealed the artwork of the song, which sees them doing thier best blue steel as they sit in front of some speakers.

Are you a fan of 5 Seconds Of Summer? Make sure you vote for them to be MTV's Hottest Summer Superstar of 2014! To vote all you need to do is tweet #MTVHottest 5SOS and watch their progress on our live leader-board at hottest.mtv.tv