Atletico Madrid received a timely fitness boost as Tiago was given the green light to return to action after more than five months on the sidelines with a fractured tibia.
The Portugal midfielder underwent surgery in November after sustaining the injury in a 1-0 win over Espanyol.
However, Tiago has made promising progress in his recovery and is available for head coach Diego Simeone ahead of a crucial run-in.
An Atletico statement read: "The Portuguese midfielder Tiago Mendes has been medically discharged after more than five months away from the playing fields.
"Our 'number five' suffered a displaced fracture in his right tibia on November 28 during the league encounter between our team and Espanyol at the Vicente Calderon.
"After a lot of hard work of recovery to overcome his injury, Tiago, who had already joined the group in training, is finally fit to compete and Diego Pablo Simeone can count on him for the matches the team is facing."
Atletico are level on points with La Liga leaders Barcelona with two matches remaining against Levante and Celta Vigo.
The capital club will also meet rivals Real Madrid in the Champions League final on May 28 in a repeat of the 2014 showpiece.