The young midfielder feels that the Premier League side's tactics allowed the Catalans to play their own game, and felt they were unfortunate to end up losing
A single Didier Drogba strike helped Chelsea to a hard-fought victory at Stamford Bridge, but Thiago was not too surprised with the Premier League side's performance.
"I don't think that we learned a great deal that was new about Chelsea. They closed up at the back and counterattacked," the midfielder said to Uefa.com.
"I don't think that's solely responsible for them winning because, in fact, their game plan partly benefited us. It allowed us possession of the ball, in good areas, and we created chances because of that.
"This hasn't even really been a 'strange day at the office', just an unfortunate one in terms of scoring the goals we should have."
Thiago then looked ahead to the second leg, and stressed Barcelona are confident they can turn things around at home.
"It's not the result we were seeking and now we'll just have to prepare for the second leg. With respect to the return we are calm and confident."
The return takes place at Camp Nou on April 24.