The BBC has selected three songs, each to be performed in two different versions by two different artists:
The songs will be performed by:
Each of the three songs will be performed in two different styles, each by a different act. The first part of the show will see three rounds of this 'song-off'. After all six acts have performed, expert judges will decide which three acts and version of each song will face the public's vote.
The judging panel consists of Eurovision super-fan and presenter Rylan Clark-Neal, popstar and BBC Radio 1 DJ Mollie King and DJ, popstar and presenter Marvin Humes.
The three final acts will then perform one more time before the lines open and the public can choose which song and performer will represent the United Kingdom in the Grand Final of the 2019 Eurovision Song Contest in Tel Aviv.
Who do you think should win tonight's show and represent the UK in May? Let us know in the comments!