Andrea Pirlo and Sergio Busquets have defined the last decade in Europe, but the Premier League still lacks equivalent deep-lying playmakers.
German club 1860 Munich have expressed interest in signing Chelsea defender Matt Miazga on loan, though a deal is unlikely, a source confirmed.
Marin made just 16 appearances for Chelsea in his debut season and had not featured for the club in three years.
Manchester City manager Pep Guardiola admitted that goalkeeper Joe Hart is being considered to play against Steaua Bucharest.
As Claudio Bravo arrives in Manchester, Pep Guardiola admits being close to discuss the deal to bring the goalkeeper to the Etihad.
Aguero has started the season in blistering fashion, scoring six goals in City's first three games.