Diego has pledged his immediate future to Atletico Madrid but stopped short of ruling out a possible return to Werder Bremen.
The Brazilian is currently on loan at the Vicente Calderon from Wolfsburg and is scheduled to return to the Volkswagen Arena at the end of the season.
However, Bremen sporting director Klaus Allofs admitted earlier this week that he would re-sign the player should the opportunity to do so arise.
Diego, for his part, insists that he is currently focused on Atletico’s Primera Division clash with Villarreal this weekend but did not close the door on a return to the Weserstadion.
“My present and my future is Atletico,” the playmaker told AS. “At this stage I’m spending all my energy on helping Atletico achieve their goals.
“When the season ends we will see, but for now I am only thinking about Villarreal as I have great respect for this team.”
Diego admitted that a win on Sunday would come as a massive boost for the players and their new coach, Diego Simeone.
“We started well enough in a tough match in Malaga and had a very good second half,” he said of Simeone’s first game at the helm.
“Villarreal will mark our recovery if we win. Simeone is doing a very important job, physically and psychologically.”
Atletico currently sit 11th in La Liga, just four points above Sunday's visitors to the Vicente Calderon, who are 18th.