Southampton have signed Celtic's England international goalkeeper Fraser Forster on a four-year contract for a fee in the region of £10m.
The 26-year-old spent four years at Celtic Park, winning three league titles and two Scottish Cups.
He was part of the England squad for this summer's World Cup in Brazil, although he did not feature.
Saints boss Ronald Koeman said he was "delighted" to sign Forster, whom he described as "very talented".
|Fraser Forster on leaving Celtic|
|"I have accepted a new opportunity, but I am a Celtic supporter for life and will be cheering the club on in everything they do."|
Forster's arrival increases the competition for first-choice goalkeeper Artur Boruc, who also played for Celtic and is out of contract next summer.
Speaking on the club's website, Koeman added: "Fraser is the perfect fit to help complement the players we already have, and he will add a lot of quality to the squad."
Forster, who set a Scottish top-flight record for consecutive league clean sheets with 13 in a row last season, said: "I know the club wanted me to stay, and I know the club has done everything they possibly can to keep me."
"But I felt now was the right time for a new challenge in the English Premier League."
Celtic boss Ronny Deila added: "Although I have only worked with Fraser for a short time, I can see that he is a top-class goalkeeper, a magnificent professional and someone who gave his all every time he pulled on the Celtic jersey."
Celtic, who were given a Champions League reprieve on Friday, turned down one offer from Saints before agreeing to sell.
|Luke Shaw||Manchester United||£27m|
They must pay 25% of the transfer fee to Newcastle, from whom they signed Forster for £2m in July 2012 after two seasons on loan.
But striker Rickie Lambert, midfielder Adam Lallana and defender Dejan Lovren have moved to Liverpool, left-back Luke Shaw has joined Manchester United, Arsenal signed right-back Calum Chambers and forward Dani Osvaldo has joined Inter Milan on loan.
In addition, Koeman, who succeeded Mauricio Pochettino in June, told BBC Sport on Friday that midfielder Morgan Schneiderlin was "not mentally or physically ready" to play.
The 24-year-old has been linked with Tottenham, but Saints chairman Ralph Krueger said he is not for sale.
The last game of Forster's four-year spell at Celtic was Tuesday's third qualifying round second leg against Legia Warsaw.
Although Celtic lost 6-1 on aggregate, they were reinstated to the competition after Legia were punished for fielding an ineligible player.