Brazil forward Neymar said he needed a new challenge, as he joined Paris St-Germain from Barcelona for a world record fee of 222m euros (£200m).
The 25-year-old won seven major trophies in his four seasons at the Nou Camp, including the Champions League once and La Liga twice.
He said his father, Neymar Sr, wanted him to stay at Barcelona.
“I have won all that a player can win,” said Neymar, who will earn 45m euros (£40.7m) a year on a five-year deal.
Writing on Instagram, he added: “I have conquered everything an athlete can conquer. I have lived unforgettable moments. But a player [me] needs challenges.
“And for the second time in my life, I’ll contradict my father.”
Neymar’s transfer smashes the previous record set when Paul Pogba returned to Manchester United from Juventus for £89m in August 2016.
His £782,000-a-week wages mean PSG’s total outlay is £400m.
The French side have called a news conference for 12:30 BST on Friday, and Neymar will be introduced to fans at PSG’s first game of the season against Amiens at Parc des Princes on Saturday.
PSG reached the last eight of the Champions League last season – knocked out by a Neymar-inspired Barcelona – and were beaten to the French title by Monaco.
Neymar said he has joined “one of the most ambitious clubs in Europe”.
“Paris St-Germain’s ambition attracted me to the club, along with the passion and the energy this brings,” he added.
“I feel ready to take the challenge. I will do everything I can to help my new team-mates.”