The 28-year-old, who played one season on loan with the Spanish outfit, winning the UEFA Europa League in 2012, was given permission to return to Spain on Friday after handing in a transfer request.
"Diego approached us with the request to be able to move to Atletico," said Bremen's sporting director Klaus Allofs. "In the end, we agreed to it, even if we would have liked to have carried on working together until the summer at least. His immediate transfer is regrettable because Diego has always acted in a highly-professional way with us, but hopefully it only means a short-term loss in quality for our team."
"We are still well-enough equipped to be able to carry on chasing our goals. We wish Diego much joy and success with Atletico," added Allofs. Diego was grateful to the Wolves for allowing him to return to Spain midway through the season. "I'd like to thank Wolfsburg, in particular Klaus Allofs and Dieter Hecking who have agreed to my request to leave and were always very open with me," he said. "I had a super time in Wolfsburg overall. Our fans always gave me excellent support and I'd like to say once again to them: many thanks! I wish Wolfsburg all the best."
Check out Diego's five greatest strikes in Germany's top flight courtesy of the Bundesliga's official YouTube channel: