The Italian defended his team's performance at Camp Nou, as well as mega signing Gareth Bale, who was replaced on the hour mark
The capital outfit fell behind to an early Neymar strike but rallied in the second half, with Luka Modric and Karim Benzema coming close to scoring while Cristiano Ronaldo had a penalty appeal rejected.
And although they ultimately succumbed to Alexis Sanchez's chip, Ancelotti was more than heartened with his men's performance and felt that he was right to start Sergio Ramos in midfield.
"The second half was great: we pressed and played better. We had control of the match," the Italian told reporters.
"I think that the penalty was so clear, only the referee didn't see it.
"I looked for the balance with Ramos in the midfield. I talked with him and he was pleased with this. I don't think that we played with three defensive midfielders.
"Modric is not one. [Sami] Khedira and Ramos were for balance in the defensive game, but we had Marcelo, [Daniel] Carvajal and the two fowards.
"Barcelona didn't played offensively, and only had Neymar and [Lionel] Messi. It was a fantastic match in a fantastic atmosphere. Obviously we wanted to win, but it was a great test."
Ancelotti opted to start Gareth Bale, but the Welshman was substituted on the hour mark after an unproductive performance.
Nevertheless, the Italian stood up for his embattled star, saying the winger fulfilled his tactical duties: "These are the first matches for Bale. He needs to learn to combine with his other team-mates.
"Bale doesn't care about whether he plays on the right or left. I asked him to play to put more pressure on [Sergio] Busquets."
Bale signed for los Blancos in a €100 million deal in September, but has featured sparingly due to persistent injury problems.