The Spaniard made his comeback against Borussia Dortmund on Saturday to set up Arjen Robben's goal and said he was grateful to have featured in the "incredible" game.
The 22-year-old had been out of action since August with ankle ligament damage but came off the bench to set up Arjen Robben's goal in the 3-0 win at Signal Iduna Park.
"I missed playing the game and having the ball in the two months off the pitch. Now I am very happy - we have won where it is hardest to do so. We're proud of this," he told TZ.
Thiago's cross-field pass released Robben to secure the points for Pep Guardiola's side on Saturday with a sublime chipped finish and the Spaniard confessed there was an element of fortune about his hurried assist.
"I only saw one player [Robben] in red. It all happened so fast. Then I saw it was Arjen and knew what was happening. Arjen has a very great quality," he said.
Thiago went on to state his gratitude to have been able to play in such a highly anticipated encounter, insisting the experience rivaled that of playing for Barcelona against Real Madrid.
"It is not better or worse than El Clasico, it's just different. The atmoshpere here is incredible, I'm just very glad I was able to play here. Now we have to think of Bayer Leverkusen, since we also have to play them, not just Dortmund."