Marc Cucurella has completed his big-money switch from Brighton to Chelsea in a blow to Manchester City.
The Citizens were keen to sign the Spanish defender but the Blues pipped their Premier League rivals with a bid that could rise to £65million.
After finalising his switch, Cucurella said: “I’m really happy. It’s a big opportunity for me to join one of the best clubs in the world and I’m going to work hard to be happy here and help the team.”
New Chelsea chairman Todd Boehly was delighted to get a move over the line and tipped the former Seagulls star to make an instant impact.
He added: “Marc is an elite defender of proven Premier League quality and he further strengthens our squad going into the new season.
“We continue to work on and off the pitch and we’re delighted Marc will be a part of the present and future at Chelsea.”
Cucurella, 24, had been a star man on the South Coast since arriving from Getafe 12 months ago, winning the club’s Player of the Season award in his first campaign.
He will now compete against Ben Chilwell for a berth on Chelsea’s left flank, with Marcos Alonso tipped to move to Barcelona.
Chilwell, 25, returned to action at the end of last season after surgery on an ACL injury but Tuchel admits the England international will need time to get back to his best.
Commenting on his plans for Cucurella and Chilwell, the Blues boss said: “Marc’s young, hungry, mobile and a very intelligent player.
“It helps in depth and quality and it helps Ben to escape the pressure of ‘I have to deliver’ and we need you absolutely now.
“Ben looks better and better but at the same time he needs a little more time to adapt to the rhythm and physicality of the match itself, which is absolutely normal.
“It’s not only about training and training exercises and little pitches, it’s at the end a very, very demanding league.
“And we have to take care about him, it’s our responsibility, so we can’t just throw him in and see what happens.
“He is impatient and we will never expect him to be fully patient, but he knows everything needs time.
“He will get the time and still we will try to put him on the pitch as soon as possible, because he’s a huge asset for us on the left side with his speed and repetition of intensity.”
When unveiling Cucurella, who has been capped once by Spain, the Blues gave fans a glimpse of their new away shirt, which has yet to be officially revealed.
And the new arrival may even get to strut his stuff for Chelsea in their season opener at Everton tomorrow.
Two players set to start at Goodison Park are Raheem Sterling and Kalidou Koulibaly, who joined the West Londoners earlier this summer following the exit of Antonio Rudiger and Andreas Christensen.
Rudiger signed for Real Madrid on a free and Christensen followed him to LaLiga with Barcelona when his contract expired, while flop record signing Romelu Lukaku has been shipped back to Inter Milan on loan.
England youth prodigy Carney Chukwuemeka also arrived at Stamford Bridge earlier this week after pushing for a departure from Aston Villa.
As a sweetener in the Cucurella deal, Chelsea whizkid Levi Colwill, 19, has joined Brighton on a season-long loan — much to the delight of Seagulls boss Graham Potter.
He said: “Levi has enormous potential and has already shown his ability last season in the Championship and with England at various age group levels up to the Under-21s.
“I am really looking forward to working with him on the training pitch and in matches over the course of the season.
“He plays mostly at centre-back but has also played on the left as a full-back. He is a player who is comfortable on the ball.”