Born in Madrid on 28 December 1990, Marcos Alonso is a fullback who is also proficient in the wing-back position and poses a threat from set-pieces. Football runs in his family, with his father, Marcos Alonso Peña, and his great grandfather, Luís Zabala, having played professionally, and his grandfather, Marcos Alonso Imaz, “Marquitos,” was a professional footballer for Barça.

After starting his career with Atlético Madrid and later joining Real Madrid, where he made his debut against Racing Santander on 4 April 2010, Alonso has spent the majority of his playing career in England. He played for Bolton Wanderers, then moved to Sunderland and went on loan to Fiorentina before being signed by Chelsea.

Alonso had great success at Stamford Bridge, with his biggest achievement being the Champions League title.

In addition to his club success, he has played for the Spanish national team, earning his debut against Argentina in 2018.