Atletico Madrid sealed a deadline day return of Brazilian playmaker Diego from Wolfsburg, two years since he left the Vicente Calderon.
The 28-year-old made 30 La Liga appearances during his single season in Spain, scoring three goals before he was sold to Wolfsburg.
With Atletico pushing for the title this season, coach Diego Simeone will hope the midfielder can help keep them on target.
While Diego arrives at Atletico, two players left the club on loan – youngster Oliver Torres joined Villarreal while 23-year-old Frenchman Joshua Guilavogui returned to former club Saint-Etienne.
Valencia midfielder Sergio Canales completed a move back to the north of Spain with a move to Real Sociedad for an undisclosed fee.
The 22-year-old signed a four-and-a-half year deal with the club, while Dorlan Pabon followed him out of the door to Sao Paulo on an 18-month loan.
It was not just outgoings at the Mestalla with Seydou Keita completing his deal until the end of the season, and Philippe Senderos arrived from Fulham for an undisclosed fee.
Sevilla agreed a deal with Napoli for defender Faouzi Ghoulam, with Hernan Perez and Thievy Bifouma also leaving La Liga for other countries in Europe.
Perez agreed a deal with Olympiacos after Villarreal accepted a bid from the Greek Super League side for the midfieder, and immediately replaced him with a more for Barcelona B left winger Juan Roman while Pepe Mel made Espanyol’s Thievy Bifouma his first West Brom signing.
Celta de Vigo completed a loan move for Spartak Moscow striker Welliton until the end of the season, while Mohamed Sissoko, who left Paris Saint-Germain at the end of last season, completed a short-term deal with Levante.
Rayo Vallecano welcome Inter Milan youngster Samuele Longo on loan for the remainder of the league campaign, and Alexander Iakovenko also moved from Italy as he agreed a loan move from Fiorentina to Malaga.