London - Manchester City signed United States goalkeeper Zack Steffen from Columbus Crew on Tuesday.
Steffen agreed a four-year contract with the Premier League champions and will move to Manchester in July as back-up to City's first-choice keeper Ederson.
The 23-year-old will remain with Columbus for the early stages of their 2019 MLS Eastern Conference campaign, which begins in March.
Columbus Crew claimed the undisclosed transfer fee for Steffen is the largest in the club's history and the most ever received by a Major League Soccer side for a goalkeeper.
"City have reached an agreement with MLS side Columbus Crew SC over the future transfer of goalkeeper Zack Steffen," a statement on City's website announced.
Steffen, who has played six times for his country, said: "Any success that I have had as a goalkeeper in MLS with Crew SC is a testament to those around me who have pushed me -- team-mates, coaches, staff, family, friends and supporters.
"Today's announcement regarding next summer is a special moment for me and I look forward to finishing my time with this club on a strong note.
"I am eager to continue to put in the work to improve and be the best team-mate I can."
Steffen began his career with Germany's Freiburg and made 14 appearances for their reserve team before moving to Columbus in 2016.
He was voted the 2018 MLS Allstate Goalkeeper of the Year after keeping 10 clean sheets.