Neither Brazil nor Ecuador could break the deadlock as the Copa America Centenario Group B fixture ended goalless in Pasadena.

After a lively start at the Rose Bowl, Sunday's (AEST) match petered out to a 0-0 draw, although the storyline was a disallowed goal for Ecuador, which was arguably unfortunate not to claim all three points.

Enner Valencia's cross-cum-shot somehow found the back of the net from the byline after a howler from Brazil goalkeeper Alisson, but the ball was deemed to have gone out of play.

Brazil was forced into two changes after edging Panama in its final pre-Copa America fixture, with Miranda dropping to the bench with a muscle problem in the build-up. Luiz Gustavo dropped out of the squad completely because of personal problems during the week, while Douglas Santos made way as Marquinhos, Casemiro and Filipe Luis came into the line-up.

After missing Ecuador's 1-0 loss to United States, Antonio Valencia returned to the starting XI, along with captain Walter Ayovi and Arturo Mina at the expense of Frickson Erazo, Cristian Ramirez and Angel Mena. Esteban Dreer replaced injured goalkeeper Alexander Dominguez.

Unlike the two early games on Sunday (AEST), the clash in Pasadena was lively from kick-off with chances at both ends, as Brazil captain Neymar watched from the stands after opting to skip the Copa America in favour of the Olympic Games in August.

Miller Bolanos went close for Ecuador after almost curling the ball inside the post from outside of the penalty area but the best opportunity fell to Philippe Coutinho, who was somehow denied by Dreer from point-blank range in the sixth minute.

As the half wore on, space opened up across the pitch with Brazil dictating play but Ecuador remaining a threat on the counter, although neither side could make the breakthrough before the interval.

Brazil keeper Alisson was spared embarrassment past the hour-mark after Enner Valencia found the back of the net from the byline but the ball was adjudged to have just crossed the line by officials.

That was the highlight of the second half, after an entertaining start to proceedings, which was reflected in the stands as the Mexican wave swept through the stadium.

Substitute Lucas Moura, though, did come close to earning maximum points with 10 minutes remaining as Dreer hesitated but the Paris Saint-Germain speedster's header flashed wide.