Midfielder Nico Gonzalez has completed a £50m move to Manchester City from Porto.
City had already sanctioned £130m of spending in the January window, bringing in Omar Marmoush, Abdukodir Khusanov and Vitor Reis.
The signing of Gonzalez has taken City's total outlay to £180m with central midfield considered a priority position to strengthen.
Gonzalez said: "This is the perfect opportunity for me at this stage of my career. I want to test myself in England. There's no better club than Manchester City for me to do that.
"There isn't a footballer in the world who would not want to be part of this setup. I know the reputation Pep has and I cannot wait to work with him. In fact, I am honoured he wants me to play in his team."
The 23-year-old joined Barcelona's academy in 2013 and made 27 appearances before joining Porto in a deal worth €8.5m in 2023. Barcelona are due 40 per cent of the fee received by Porto.
Gonzalez, who had been monitored by Man City since he was a teenager, has scored seven goals and recorded six assists in 29 appearances so far this season.
City were thrashed 5-1 by Arsenal at the Emirates on Sunday and are now 15 points behind Premier League leaders Liverpool.
Director of football Txiki Begiristain added: "Nico is a very talented young midfielder. He is an ideal acquisition for Manchester City.
"It was a difficult transfer to complete because his performances have been outstanding, and he has been such an important part of what FC Porto are doing this season. We are really happy we have managed to get this done before the window closed."
Man City needed to strengthen: They are being ravaged
Sky Sports' Gary Neville:
"They are getting ravaged and dismantled in midfield. There are fantastic players in there but there is no balance.
"Bernardo Silva and Mateo Kovacic when the tempo increased against Arsenal, it was so difficult for them. Man City needed to strengthen."
Merson: City panicking badly on Gonzalez
Sky Sports' Paul Merson on Deadline Day:
"I've not seen this lad play so don't know too much about him. But they need players in midfield. A lot of people say it's not just Rodri. It is just Rodri.
"Rodri sees danger, Rodri is disciplined, Rodri stays in the centre, he gets forward and sits back and protects the backline as well, and he passes the ball through the line very quickly.
"I like Mateo Kovacic but he will go over and dribble with the ball and people end up all out of position. He and Bernardo Silva got ruined in the last 30 minutes at Arsenal.
"If you take away the 30 minutes and first 20, City were very good at Arsenal. It was a good away performance.
"The issue is that Gonzalez comes in for £50m, as soon as Rodri's fit, that's it. I don't think he plays. Unless you play them together and I don't think you need to.
"This is the problem with wages and buying players, you forget that by the start of next season, this guy is sitting on the bench with big money. You then look at James McAtee with a brilliant future and they will have to sell him for the fair play rules. It's a knock-on effect. If they buy Gonzalez, they must be panicking badly to get into the top four."
