River Plate and Boca Juniors — the most explosive derby in South American football and perhaps anywhere else — meet again in the Copa Libertadores for the second time in ten months. Instead of meeting in the final, this time they will meet in the semifinal over two legs. There are some differences in this two-match encounter: first, there will be no extra time at the end of the second leg, and second, away goals matter.

Boca Juniors have a different manager on the touchlines in Gustavo Alfaro, who joined in January after Guillermo Barros Schelotto left for the LA Galaxy. It’s taken some time for Alfaro to settle upon an ideal starting lineup, but he appears to have found a core of players that he can rely upon for Libertadores play. In the quarterfinal tie against Liga de Quito, he stuck with the same starting lineup with Estebán Andrada in goal, Marcelo Weigandt and Emmanuel Mas as wing backs, Lisandro López and Carlos Izquierdoz as center backs, Iván Marcone as a holding midfielder, Nicolás Capaldo positioned a little further ahead, Eduardo Salvío and Alexis Mac Allister out wide and Ramón Ábila and Carlos Tevez as the forwards.

Will Alfaro stay with this lineup for the semifinal first leg? I doubt it. I’m not sure where Boca will find the goals from open play with such a lineup. Ábila has been valuable for Boca in recent years, but this season the more effective striker has been Mauro Zárate, and he appears to be injured. Boca could rely on set pieces for their scoring opportunities, and they have been the best in the competition at set-piece xG. Another thing to consider is that Carlos Tevez has been more effective at this point in his career as a provider than a goalscorer. But Mac Allister has demonstrated himself to be an excellent creator, so is Tevez necessary at the beginning? These are questions that probably won’t get resolved until just before kickoff.

As for River, Marcelo Gallardo remains in charge after securing his second Libertadores in December. He has had to cope with the loss of two important pieces of his midfield — Juan Fernando Quintero to an ACL injury and Pity Martínez to Atlanta United in Major League Soccer. There have been more changes to his lineups in the knockout stage, but he appears to have settled upon a backline of four and the trident up front. Below is the passing network of his team from the quarterfinal second leg against Cerro Porteño:

River boast a very potent lineup up front — Lucas Pratto, Rafael Borré, and Lucas Martínez are in the top 30 in total xG among all Libertadores players, and Pratto, Borré, and Diego De La Cruz rank in the top 20 in xA from open play. Gallardo likes to get a lot of the ball through his wing backs, whether Gustavo Montiel or Milton Casco. But the most dangerous central player will be Exequiel Palacios. The outcome of the individual battle between Palacios and whoever draws that assignment for Boca (either Marcone or Capaldo) will go a long way to deciding the outcome of the tie.

A few weeks ago, River and Boca met in the league and played to a dull 0-0 draw. I believe tonight’s first leg will be just as cagey because of what’s at stake, so a 0-0 scoreline is just as possible. If goals are in the forecast, I expect that it will be scored, more likely, by River.