Celta Vigo left-back Javi Galán is set to join Atlético Madrid in a transfer worth around €3.5 million, sources have confirmed to ESPN.
Atlético youngster Manu Sánchez will move in the other direction as part of the deal.
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Galán's arrival ends Atlético's search for a permanent left-back following Renan Lodi's move to Nottingham Forest last year and an injury to Reinildo.
Sergio Reguilón joined on loan from Tottenham last season but, for various reasons, did not nail down a regular starting sport and coach Diego Simeone was forced to improvise with personnel and his formation.
Galán, 28, was a regular for Celta last season, making 40 appearances in all competitions, and has previously been linked with Barcelona.
The good relationship between Atlético CEO Miguel Ángel Gil Marín and Celta president Carlos Mouriño facilitated the agreement, which will see Sanchez move in the other direction.
Sánchez, 22, is also a left-back and did well on loan at Osasuna last season but Simeone has preferred to move for Galán to reinforce the position.
Atlético still want to further strengthen their squad this summer after their fine form in the second half of the season saw them finish third in LaLiga, just one point behind Real Madrid.
However, the lack of outgoings so far is limiting how many players they can bring in.
Celta, meanwhile, have recently appointed Rafa Benítez as their new coach as they look to improve on a year that saw them survive relegation on the final day of the campaign.