River Plate's game plan gives them crucial first-leg win over Lanus

There were plenty of fireworks as River Plate and Lanus took the field for the first leg of an all-Argentine Copa Libertadores semifinal.

The fans had to wait 81 minutes for the main explosion of the night, Ignacio Scocco's goal which gave River a 1-0 win. But this was an absorbing game, in which River's first-leg lead was the result of a victory in the battle of ideas.

The game plan of Lanus is the same as it has been for a couple of seasons. Under coach Jorge Almiron they have shown admirable continuity. This was essentially the same lineup as the one which beat River 3-0 back at the start of February in a Supercup clash that kicked off Argentina's domestic campaign. Lanus play a 4-3-3 formation, with veteran centre forward Jose Sand supported by the quick, sinuous wing play of Alejandro Silva and Lautaro Acosta.

Well beaten in that match back in February, this time River coach Marcelo Gallardo responded with a with a much-changed team and a different idea. He sought to achieve numerical superiority deep inside the Lanus half. This forced Silva and Acosta to drop deep and defend, leaving Sand isolated.

Lanus were left without attacking pace. River's attacking midfielders -- Gonzalo Martinez and Nacho Fernandez -- moved fluidly across the line, supporting centre forward Scocco and leaving a corridor for the side's young attacking full-backs, Gonzalo Montiel and Marcelo Saracchi. They were involved in setting up most of River's first-half chances, constantly looking to supply Scocco with early crosses.

The risk was that in River would over-commit to their attack and leave themselves open to the counter, exposing the lack of pace of their centre-backs. Lanus launched one dangerous break out in the first half, with Acosta only stopped by a desperate tackle from Montiel. And in the second there was a moment when Acosta threatened to get behind River centre back Javier Pinola.

The vast majority of the play, though, was taking place at the other end of the field. Pinola was so far up the pitch that he came closest to opening the scoring, thudding a 25-yard shot against the post after Martinez and Fernandez combined down the right.

Fernandez then gave way to young Uruguayan attacking midfielder Nicolas De La Cruz, who played a neat pass from the edge of the area to Martinez in the left channel. His fierce cross shot was blocked by Lanus keeper Esteban Andrada, and Scocco reacted the quickest to turn home the rebound left-footed from a tight angle.

River Plate were well worth their win, and will be seen as favourites to make it through to the final -- especially since they did not concede an away goal. Lanus were in a worse position against similar opposition after the first leg of the quarterfinal, though; they were 2-0 down against another Buenos Aires giant, 2014 champions San Lorenzo, and managed to save themselves, coming through a penalty shoot out. Can they pull off another rescue act against the 2015 winners?

The answer will be supplied next Tuesday. But now the focus switches to the first leg of the other semifinal, Wednesday's meeting between Barcelona of Ecuador and Gremio of Brazil.