LA Galaxy defender Julian Araujo sealed a permanent move from the MLS team to Spanish giants Barcelona on Friday.
Paperwork for the transfer reportedly arrived 18 seconds after the deadline for LaLiga signings in January, causing a delay.
Araujo has now been able to make the move and is initially joining up with Barcelona's B team, Barca Atletic.
The Mexico international has signed a three-and-a-half-year deal, Barcelona said.
Barcelona have reportedly asked the Court of Arbitration for Sport to rule on whether Araujo should be allowed to play competitive games this season.
In the United States, reports said Barcelona would pay €3.7million ($4m) for the 21-year-old, with the Galaxy confirming they negotiated a sell-on clause in the deal.
Announcing his departure in an Instagram post, Araujo penned a goodbye letter to the Galaxy, saying he and team-mates "fought together, side by side, for four amazing seasons that I'll never forget".
"A big thanks to the incredible fans who cheered me on from my debut to my final game," he added. "To all of my team-mates, coaches and staff, it was a pleasure to represent the badge alongside all of you. I am very grateful to have been given the opportunity to develop from an academy member to a first team player, with the biggest club in MLS.
"LA Galaxy will always be a part of my story and it was an honour to share these experiences with all of you. See you soon."
Galaxy head coach and sporting director Greg Vanney said two-time All-Star Araujo deserved the chance to go to Camp Nou.
Vanney said: "It's a wonderful story of a young Southern California native who came to the LA Galaxy academy with a dream of playing for the LA Galaxy.
"He's played now three years inside of the first team and he's been recognised for his growth and the effort he's put in and how we've been able to support him over that time.
"To have clubs like Barcelona come and have interest in Jules shows, a) his effort, and b) how the process can work as you work through the LA Galaxy.
"Now he's going to be moving to one of the biggest clubs in the world, which is exciting in many ways for him and his story. This is by no means the end of Julian's story, this is just the next chapter."
