Former Manchester City and England goalkeeper Joe Hart said he wants to "smash through the finishing line" with Celtic as he announced Thursday he was retiring at the end of the season.
Hart will be 37 when his three-year contract with the Scottish Premiership champions expires.
He won 75 England caps and played 348 times for Manchester City, winning two Premier League titles.
Hart helped Celtic win five out of six domestic trophies in the past two seasons under Ange Postecoglou, who is now managing Tottenham.
Celtic trail rivals Rangers by two points in the Premiership and the goalkeeper, who joined the club from Tottenham in 2021, promised fans he remains up for the fight.
"Mentally I'm in that one place that I like to be, I'm in a place of clarity," he told Celtic TV. "Obviously, I've thought about this a lot.
"I think the right time is now. I've got the clarity of mind that I was able to go to the club and explain my position and them totally understand."
He added: "I am aware time waits for no man and I don't want my body to be retiring me. That was one of the key factors, thinking I can smash through the finish line."
Celtic boss Brendan Rodgers praised Hart's "phenomenal career".
"For all he has done in football, Joe deserves huge praise and congratulations," he said in a club statement.
"He has been such a brilliant asset to Celtic of course and the wider game at the highest levels, domestically and internationally.
"But more than that, he is a tremendous man, just brilliant to work with."