Here are some other high-profile player who left clubs and later re-signed for them, often for a much bigger transfer fee:
Cesc Fabregas
Fabregas joined Arsenal from Barcelona in 2003 on a free transfer at age 16. He became a star under Arsene Wenger, as a replacement for Patrick Vieira in central midfield, and it wasn't long before his former club showed an interest in bringing him back to Spain. Eight years after leaving Camp Nou, Barcelona and Arsenal agreed a deal worth £35 million for the midfielder. Fabregas has since returned to London, signing for Chelsea in 2014.
Nemanja Matic
Serbia midfielder Nemanja Matic initially signed for Chelsea in 2009 for £1.5 million. He spent two years at Stamford Bridge before being deemed surplus to requirements, leaving for Portugal as a makeweight in a deal that brought David Luiz to Chelsea from Benfica for £25 million. Matic spent three successful years at Benfica before Chelsea manager Jose Mourinho decided to re-sign him in 2014 for £21 million.
Nicolas Anelka
Having started his career at Paris Saint-Germain, Anelka signed for Arsenal at age 17 for £500,000 in 1997 and helped the team win the Premier League. The France striker moved to Real Madrid two years later for around £22 million, before PSG spent a similar amount to bring him back to France.
Dani Carvajal
Carvajal signed terms with Real Madrid at the age of 10 and spent his entire youth career there, eventually playing for its reserve side, Real Madrid Castilla. After failing to make an appearance for the first team, Carvajal was sold to German side Bayer Leverkusen in 2012 for €5 million. Real Madrid had ensured a buy-back clause was inserted into the deal and, just a year after leaving, Carvajal re-signed for Madrid in 2013 for a deal worth €6.5 million.
Gerard Pique
Pique left current club Barcelona for Manchester United in 2004 at the age of 17 on a free transfer as he was deemed too young to be considered a professional. After four years and limited first-team action at United, including a short loan at Spanish side Real Zaragoza, Barcelona decided to spend £5 million to bring Pique back to the club in 2008. He has proved a big success at Camp Nou, winning 14 major trophies as well as the World Cup and European Championship with Spain.
Alvaro Morata
Morata left Real Madrid in 2014 after four seasons there and joined Juventus. The terms of the move included a buy-back option and Madrid exercised that option this offseason, with the fee reported to be up to €30 million. Morata had impressed for Spain at Euro 2016.