Attacker Doyle is a USA Under-23 international forward who joined Derby County in the summer of 2010 after a successful trial spell.
He originates from Texas in America and gave up his scholarship at Creighton University in Nebraska to follow his dream of a professional career across the Atlantic Ocean.
Doyle played for Dallas Texans at youth level, which is where he came to the attention of the Rams and he was invited over for a trial during pre-season ahead of the 2010-11 campaign.
His performances impressed Derby's coaching staff enough to hand him a permanent deal and he made his first senior start just two weeks later in Derby's 2-1 defeat to Coventry City, and he went on to make a further four starts and six appearances from the bench for the first-team during the season.
He made only six appearances in 2011-12 with ankle and hamstring injuries preventing him from first-team appearances, with his only start coming in November 2011 against Peterborough United.
Appendicitis limited him to just a single start in 2012-13, as well as a handful of substitute appearances. Although he is an out-and-out striker, Doyle can also play in midfield to provide an attacking outlet from deep.
Through his father Doyle qualified for the Republic of Ireland and he represented them at Under-21 level before deciding to pledge his allegiance to the US – and has since been a regular in the USA youth squads.
In July 2013, he joined MLS side DC United on loan until the end of their 2013 season.