Education
Born in Parla in the Community of Madrid, Calero graduated from local Atlético Madrid"s youth system, and made his senior debut with the C-team in the 2011-2012 campaign, in Tercera División.
Born in Parla in the Community of Madrid, Calero graduated from local Atlético Madrid"s youth system, and made his senior debut with the C-team in the 2011-2012 campaign, in Tercera División.
He began his career at Atlético Madrid, playing in its third and second teams before joining Derby in 2014. Calero has represented Spain internationally, up to under-19 level Atlético Madrid
He appeared regularly in the following season, also making his senior debut with the reserves in Segunda División B on 9 September 2012, replacing Pedro Martín after 60 minutes of a 1–3 loss at Civil Defense Leganéson
On 20 February 2013 Calero was called up to the main squad by manager Diego Simeone for a Union of European Football Associations Europa League match against Rubin Kazan.
Derby County
In July 2014, Calero went on a trial at Championship club Derby County, and signed a two-year deal with the Rams on 18 July. Manager Steve McLaren said "He"s a young player with excellent pedigree.
We are really pleased that he sees his future at Derby County."
Calero played his first match as a professional on 26 August, replacing Simon Dawkins for the last 20 minutes of a League Cup victory over Charlton Athletic at Pride Park, netting the game"s only goal in the 87th minute. After spending time training there, Calero was loaned to nearby League Two club Burton Albion for a month on 2 February 2015.
He was signed by Jimmy Floyd Hasselbaink, whom he had watched play for Atlético Madrid in 1999–2000, and said "He was a big hero because of his goals.
He"s one of the reasons I came..I can learn many things from him. lieutenant"s a great opportunity for my development and to get some experience". On 10 February he made his first start in his first match at the Pirelli Stadium, playing the first 64 minutes of a goalless draw against Wimbledon before being replaced by Abdenasser El Khayati.
After Calero returned to Derby, Burton were promoted to League One at the end of the season as champions, while Derby missed out on the play-offs with a 0–3 home defeat to Reading on the last day.
On 23 November 2010 Calero was called up to the Spain under-16s. He subsequently represented the under-17, under-18 and under-19 levels.