The accomplished Mexico attacker failed to settle at Spurs and has left the club permanently after a string of loan deals, arriving in La Liga hoping for more first team football
The 23-year-old attacker rose through the academy at Barcelona and signed for Spurs under manager Juande Ramos after leaving the Blaugrana in summer 2008, but failed to settle at White Hart Lane under new manager Harry Redknapp after the Spanish coach was dismissed.
Dos Santos, who can play wide in attack or in support of a striker, rarely featuring in the Spurs line-up and went out on loan over the next three seasons to Ipswich Town, Galatasaray and Racing Santander, where he scored five goals from 16 appearances in 2010-11.
In that time he has however scored 15 goals from 58 caps for the Mexico national team, winning the Concacaf Gold Cup in 2009 and 2011 and being voted runner-up for the FIFA Young Player of the Tournament award at the 2010 World Cup.
This summer he scored three goals as El Tricolor won the Olympic Gold medal in London 2012, but he was forced to sit out the final through injury.
His departure from Spurs adds to the list of creative players leaving White Hart Lane, with Luka Modric, Rafael van der Vaart and Steven Pienaar allowed to move on by Andre Villas-Boas