According to ESPN Brasil, Atletico Madrid, Juventus and AC Milan have also made contact with Brentford over Thiago's availability, though the Italian clubs are considered unlikely to match the asking price.
Brentford have set a valuation of £80 million — more than double the £30 million they paid Club Brugge to sign him in 2024 — and have no intention of selling for less after tying Thiago down to a new contract until 2031 in February.
Thiago has scored 21 Premier League goals this season, second only to Erling Haaland of Manchester City, who leads the race by three. In all competitions he has netted 24 times in 36 appearances. He also earned his first senior Brazil call-up in March and is expected to be part of Carlo Ancelotti's World Cup squad.
His first season at Brentford was largely lost to injury, limiting him to eight appearances after arriving from Belgium. The departure of Yoane Wissa last summer opened the door for a full campaign as the first-choice number nine, and Thiago has not looked back.
Brentford manager Keith Andrews has acknowledged the difficulty of retaining elite talent at the club.
"He has earned his journey. He has had to graft in his footballing career."
Chelsea's interest is driven by a need for a reliable central striker. The club will have five forwards on their books at the end of the season with Nicolas Jackson returning from his loan at Bayern Munich and Emmanuel Emegha joining from Strasbourg.
Whether any of those options satisfy head coach Liam Rosenior's requirements at centre forward remains the central question as the transfer window approaches.
Atlético are operating in a different financial bracket and are considered a more credible alternative to Chelsea at this stage, with their Champions League semi-final status giving Thiago's camp a strong European option to weigh.