The 31-year-old left-back has been an important player for the west London giants during the 2021-22 campaign, featuring 27 times in all competitions, registering one goal and three assists so far.
Alonso had been mentioned with a move away from the Stamford Bridge outfit earlier this season, but he won’t be allowed to depart in January following Ben Chilwell’s season-ending knee operation.
The Spaniard is in the final 18 months of his existing deal with the Premier League side, though, and there have been suggestions that the player could be on the move in the summer.
According to Marca, Los Rojiblancos boss Diego Simeone views Marcos as a leading target, with the Argentine head coach determined to bring in a new left-sided wing-back ahead of next term.
Marcos, who started his professional career with Atletico’s city rivals Real Madrid, has scored 25 times and picked up 20 assists in 193 appearances for Thomas Tuchel’s side in all competitions.
In other news, Chelsea centre-half Antonio Rudiger is allegedly holding out for a fresh contract worth £46 million in total with the club’s opening offer of £135,000 a week ‘upsetting’ the former Roma star.