Samir Nasri has signed with West Ham after completing an 18-month doping ban.

The 31-year-old is reunited with Manuel Pellegrini. The duo won two Premier League titles at Manchester City. 

“Samir will give us another dimension in our attacking play. He is a very technical player, with excellent quality on the ball, and the ability to create big moments in important matches," said Pellegrini.

Brek Shea has joined Atlanta United on a one-year contract.

The 28-year-old Shea was out of contract after the Vancouver Whitecaps failed to pick up his option. Atlanta will be his fourth team in MLS.

The left winger has 34 caps with the USMNT, although he hasn't played with the national team since October 2015. 

Guillermo Barros Schelotto has agreed to take over as Los Angeles Galaxy manager.

Although the contract will not be signed until next week, it is rumored to be over two years.

Schelotto won an MLS Cup as a player with the Columbus Crew in 2008. The 45-year-old most recently lead Boca Juniors to two domestic titles. 

Celtic have signed 15-year-old Karamoko Dembele to a professional contract through 2021.

Dembele originally came to the club in 2013 and made his U-20 debut in 2016 at the age of 13-years-old.

Dembele has played for England and Scotland at the youth level, but is also eligible to represent Ivory Coast. 

“My goal is to play for the first team. As soon as I can, I’m going to try to get into the first team, 100%. In the reserves, every training session, every game – it’s all to prove myself to the manager that I can play in the first team.”

Frank de Boer was named the new manager of Atlanta United, replacing Tata Martino.

De Boer is the second manager in the club's history.

Atlanta United president Darren Eales said that de Boer's attacking philosophy and player development made the difference.

“When we began our search, we were determined to find someone who fit all of our criteria. In addition to meeting our club’s core values, Frank’s philosophical views for how to play unequivocally aligns with ours. He also has a proven track record of developing youth players, with many of them going on to star for top European teams. Finally, his multilingual capabilities, including Spanish and English, ensure a smooth transition in the leadership of our club," said Eales.

Vice president Carlos Bocanegra added that de Boer's "tactics feature an attacking, high-intensity style that mirrors our approach to the game. And his track record for player development, of pushing youth players into the First Team, speaks for itself.”

De Boer won three titles as manager of Ajax, but failed to replicate that success at Internazionale and Crystal Palace. 

Alex Sandro signed a new contract with Juventus that keeps him at the club through 2023.

In his 134 matches with Juventus, he leads the club in most ball recoveries and is second in successful dribbles.

Sandro was a rumored target for Manchester United and Chelsea before the new deal.

Manchester United have exercised an option in the contract of Anthony Martial to extend his deal until 2020.

Martial's contract was set to expire at the end of the current season. It follows their decision to trigger a similar option in David De Gea's contract.

United are in talks with Martial's representatives about a longer deal.

Despite struggling in the relegation zone with two wins on the season, former Athletic Bilbao players and executives would rather see the team go down to the second division than change their Basque-only recruitment philosophy.

Athletic have never been relegated in their 120-year history. 

The club recently fired Eduardo Berizzo, replacing him with Gaizka Garitano who was in charge of the B team. 

In regards to the upcoming December election for club president, former Athletic president Jose Julian Lertxundi said "anyone who is a candidate and aspires to change [the Basque-only player mandate]... isn't a candidate. You don't even touch the philosophy".

The Basque region makes up just 4.9% of Spain's population. 

The LA Galaxy will re-sign Zlatan Ibrahimovic as a Designated Player.

The move means the Galaxy will have to move one of their three existing DPs -- Gio dos Santos, Jonathan dos Santos, and Romain Alessandrini to another club.

Ibrahimovic was already under contract for 2019 but had long chafed over a deal that paid him just $1.5 million in 2018, despite him scoring 22 goals along with 10 assists.

Manchester City has agreed to a five-and-a-half year extension with Phil Foden that keeps him with the club through 2024.

Foden has become a first-team squad regular this season at the age of 18.

Txiki Begiristain, the club’s sporting director, said: “We are delighted to have secured Phil for the next five-and-a-half years. He is an outstanding talent and he is Manchester City born and bred, so this is where he wants to play his football. Under Pep and with the players we have here around him, he is in the best place possible to develop as a player.”