Everton have signed Belgium midfielder Amadou Onana from Lille for £33m.
The 20-year-old was at Goodison Park on Saturday to watch Everton's 1-0 defeat by Chelsea in their opening Premier League game of the season
West Ham were also interested in Onana and had agreed a fee for the player.
Onana becomes Everton's fifth signing of the summer after James Tarkowski, Dwight McNeil and loan pair Ruben Vinagre and Conor Coady.
Onana, who made his Belgium debut against the Netherlands in June, said Everton manager Frank Lampard was a key figure in his decision to move.
"Everyone here showed they really wanted me and they have a plan for me," he said.
"I really appreciated the talks I had with the manager and director of football (Kevin Thelwell). They told me how they wanted me to play and I enjoyed it.
"The manager played at the highest level, won many things and was a midfielder too. It means a lot to have interest from him and I think he can teach me many things.
"They both have a lot of ambition and that's the type of guy I am, so it matches."
Lampard said: "Amadou is a player we were really keen to bring to Everton.
"He has many great qualities to help strengthen our midfield and, at just 20 years old, has massive potential to get even better.
"I spoke to him about why Everton was the right club for him and we're all looking forward to him showing what he can bring to the team."
