It was clear that River would enjoy the majority of the possession, would weave their patterns, would use the full width of the pitch. What was in question was whether they could defend against the pace, talent and aerial prowess of the Palmeiras attack.
The answer, in a first leg that comes close to defining the tie, was emphatic, with Palmeiras taking a 3-0 lead back to Sao Paulo for next week's return game.
The result is all the more striking given that Palmeiras had to change their stable defensive unit in the pre-match warm up. Centre-back Luan pulled out with an injury, and was replaced by recent signing Alan Empereur. The new recruit is left-footed, which forced captain Gustavo Gomez to switch to the right, alongside full-back Marcos Rocha, the man seen by many as Palmeiras' weak link.
River coach Marcelo Gallardo certainly seemed to think so. He started his flank striker Matias Suarez on the left, to specifically run at Rocha. It was an immediate success, with only a reflex block from keeper Weverton preventing Jorge Carrascal from opening the scoring from a Suarez cross. Rocha tucked inside, almost like a third centre-back, with Gabriel Menino, one of the midfield trio, taking care of the flank.
There were problems here. Essentially it meant that Palmeiras were defending with a line of five, leaving them outnumbered in midfield and allowing River to get into their attractive groove. And it left Matias Vina on the other flank isolated in dealing with the threat of Gonzalo Montiel, River's attacking right-back.
But just when things were looking tricky for Palmeiras, the game was changed by a combination of Menino finding space higher up the field and the River defence's tendency to self-destruct. Menino put in a routine low cross, keeper Franco Armani got in a muddle with his defender and foolishly opted to kick out, passing the ball straight to winger Rony who, with the aid of a slight deflection, struck the ball into the net.
River, however, continued to knock on the door. Twice they grazed the crossbar and good chances went wide, but it was always likely to be interesting to see how their defence could cope with Luiz Adriano. Fit and firing, there is no better centre-forward in South America, and just after half-time he defined the game, turning Robert Rojas with absurd ease on the halfway line and racing away to beat the keeper with a cool finish.
River's hopes of regrouping at the interval had been swiftly dashed, and it was too much for one of their players to take. Just before the hour, Carrascal lost his head and launched into a wild tackle on Menino and was shown a straight red card. From the ensuing free kick, whipped in from deep right by the left-footed Gustavo Scarpa, no one tracked the run of Vina, who glanced his header into the far corner.
A man up with half an hour to go, against a side who had lost both their tactical and emotional balance, Palmeiras might have done more to end the first leg with an even greater margin of victory. If they end up regretting it, then it will mean that Gallardo and his men come up with something sensational in Sao Paulo next Tuesday.