Coquimbo Unido are dreaming. The Piratas have ridden a wave of belief through this Libertadores run, and the fortress of Estadio Francisco Sánchez Rumoroso is humming. They know the history, though: four previous Libertadores ties against Argentine sides, four defeats, and not a single goal scored away from home in those matches. That is the scar tissue. But this is a home leg, and the mood in the port city is different. They've been grinding out results, staying compact, and waiting for their moments. The 0-1 away loss in the first leg — if that's the result — was a narrow defeat, not a capitulation. They created chances, they kept it tight, and they come back to their own turf with everything to play for.

Platense, meanwhile, are the ultimate spoilers. They finished runner-up in their group, and they've built their entire identity on being horrible to play against. They're the kind of side that will sit in a low block, absorb pressure, and nick a goal on the counter or from a set-piece. Their recent form shows a team that doesn't concede many, but also doesn't score many. They're happy to win 1-0, or draw 0-0 and take their chances in a shootout. That mentality is dangerous in a two-legged tie, but it also leaves the door open for a home side that needs to be brave. Coquimbo have the momentum of a crowd behind them, and they know a single goal changes the entire complexion of the tie.