West Ham have signed Portuguese Under-21 midfielder Mateus Fernandes from second-tier Championship side Southampton, the Premier League club announced Friday.
The 21-year-old has agreed a five-year deal to sign for the struggling London side in a fee reported to be worth more than £40 million ($54 million).
The Hammers, who face Nottingham Forest at the City Ground on Sunday, are bottom of the table, having lost both of their matches so far.
West Ham were also knocked out of the English League Cup earlier this week after they surrendered a two-goal lead over Wolves.
"I'm very happy to be here, and I'm very excited to play for West Ham," said Fernandes, who endured a tough Premier League baptism last season with Southampton as they were relegated.
Welcome to West Ham, Mateus Fernandes! 🤝@CorpayFX✍️✅ pic.twitter.com/26Dws5HOeZ
— West Ham United (@WestHam) August 29, 2025
"It's a big step for me. It's a big club, a massive club. The project, the stadium, the city, everything.
"I want to try to play football, enjoy football, not just run and try to score, but try to play good football. The most important thing is to try to give everything every day."
Under-pressure Hammers manager Graham Potter added: "Mateus is a young player who has made impressive progress in the early part of his career, and we are delighted to have secured his signing.
"He gained valuable experience in the Premier League last year with Southampton and is someone we really feel can help improve us and fit into what we are trying to build and develop at the club.
"We believe that his attributes and strengths will bring a different dimension to the squad and, from speaking to him, I know that he can't wait to get started here.
"He has shown great maturity and character for someone so young, and we look forward to seeing his continued progress and impact at West Ham United."