NYCFC's Jack Harrison signs for Man City, joins Middlesbrough on loan

Manchester City have completed the signing of England under-21 midfielder Jack Harrison from New York City FC and loaned him to Middlesbrough for the rest of the season.

City and MLS side NYCFC are affiliated through their City Football Group parent company, and the Premier League club used that link to bring Harrison back to his native UK on a three-and-a-half-year deal.

The terms of Tuesday's deal were not disclosed, but sources confirmed to ESPN FC's Jeff Carlisle that Man City will pay a fee of around $6 million (4.25m), which could move higher based on performances.

A portion of any fee will go to MLS, and NYCFC will be able to use up to $750,000 of its share as general allocation money toward future signings under MLS salary budget rules.

The move completes an unusual path to professional football in England for Harrison, 21, who left Manchester United's academy at 14 to move to the United States on a prep scholarship.

After playing a year at Wake Forest University, Harrison was the top pick in the MLS draft for college players ahead of the 2016 season, and impressed under coach Patrick Vieira. He scored 10 goals with six assists in MLS last season and earned a pair of call-ups to the England under-21 squad.

"It's been a pleasure to work with him over the last two seasons and he's developed very quickly thanks to his hard work and talent," Vieira said in a statement. "Jack is incredibly passionate about the game and is always looking to improve himself.

"We wish Jack all the very best as he begins the next chapter of his career. We're all looking forward to following his progress in Europe."

Harrison will now join Middlesbrough on loan in the Championship as Tony Pulis looks to challenge for promotion back to the Premier League. Boro are four points outside the playoff spots with a game in hand on sixth-place Fulham.

"I can't wait to get started over here," Harrison told City's website. "I've really enjoyed my time with New York City and I'd like to thank Patrick Vieira and his coaching staff for helping me to develop as a player.

"I feel I've really improved working under him and playing regularly in the MLS, but now I'm looking forward to testing myself in England. Middlesbrough are a good club, with Premier League experience and they're in the mix for a return via the playoffs this season. Hopefully I can help them achieve that."

Stoke City had hoped to land Harrison, with sources telling ESPN FC that the club had made a bid of$4.5m (3.25m), but the Stoke Sentinel reported on Monday that they were "consistently thwarted by a moving of the goalposts on price."

Man City's move for Harrison uses a similar tactic as their signing of NYCFC'sMix Diskerud on Saturday, where the Premier League side will take the players off the MLS club's books before looking to move them on to another team. However, Harrison appears to have a much brighter future than U.S. international Diskerud, who was largely unwanted by Vieira at NYCFC.

It's also similar to the deal that brought Aaron Mooy to City from sister club Melbourne City in 2016. Mooy immediately went on loan to Huddersfield, who signed him for 8m after winning promotion to the Premier League.

"It's a testament to our coaching, training and scouting staff that they have helped to develop Jack into a player who has garnered interest from various clubs in Europe," NYCFC director Claudio Reyna said. "It speaks to the future of our club and soccer in the U.S. We scouted Jack from an early age and he's now made appearances for England U21s.

"Of course it's sad to see Jack go but, at the same time, we recognise this is an opportunity that he felt ready for and wanted."

Speaking to ESPN last week, Harrison, who was born in Stoke-on-Trent, made no secret that it was a goal to play in the Premier League one day.

"Everyone dreams of playing in the top leagues in Europe. The Premier League is one of the top leagues there," he said. "It would be a dream to play there."

Harrison told NYCFC's website on Tuesday that he will "forever be grateful to everyone at New York City FC for having faith in me and trading up for me in the 2016 MLS draft. NYCFC has felt like home from the moment I arrived and has given me some of the best experiences of my life."