Lanus effectively have one foot in the final already, coming into this tie with that all-important away goal, the only thing that separates the two sides.
It proved to be a fascinating contest between these two sides last time out, with Mauricio Pellegrino's Velez dominating possession, but ultimately failing to make the most of it.
Lanus, on the other hand, proved to be particularly bold in front of goal, almost matching the home side in regard to shots on target, and, more importantly, converting one of their chances just before half time.
It was the 40-year-old Jose Sand that came up with the goods during his side's hour of need, and Lanus boss Luis Zubeldia will hope the veteran marksman will have it in him to be just as ruthless in this week's tie.
Pellegrino may well have regrets going into the second leg, knowing that Velez had their opportunities against Granate, but could not make them count.
Both sides will come into this game on the back of weekend victories in the Argentine Primera Division. Zubeldia's Lanus proved to be swift and decisive in their 2-0 win over Rosario Central at La Fortaleza, with both goals coming inside half an hour.
Velez, in comparison, were pegged back and pushed hard by Godoy Cruz, losing the lead on two occasions before Augustin Mulet found his side a winner just after the hour mark.
The game ended 3-2 to the home side, but Pellegrino's men were certainly forced to work for their three points. Trusted goalscorer Cristian Tarragona was even shown a red card just after Mulet's winner.
There is no doubt that fans in Buenos Aires will be hoping that both sides bring their weekend form into this week's second leg.
Lanus Copa Sudamericana form: LLWDWW
Lanus form (all competitions): WDLDWW
Velez Sarsfield Copa Sudamericana form: WWWLWL
Velez Sarsfield form (all competitions): WWLWLW
Zubeldia rested many of his key players at the weekend in preparation for this week's second leg.
While the Santa Rosa-born coach has no fresh injury concerns going into this game, he may well have a quiet selection headache after some good performances from his rotated starting XI against Rosario.
Pellegrino also opted for mass rotation, offering his key players a rest before this clash. Tarragona's sending-off will not make him ineligible to feature in this tie.
The Velez boss will likely revert to his preferred target man up front, flanked by the likes of Agustin Bouzat and Lucas Janson.
Lanus possible starting lineup:
Morales; Aguirre, Burdisso, Perez, Bernabei; De la Vega, Quignon, Acosta, Belmonte; Orsini, Sand
Velez Sarsfield possible starting lineup:
Hoyos; Guidara, Giannetti, Abram, Ortega; Centurion, Galdames, Alvarez; Bouzat, Tarragona, Janson
We say: Lanus 2-0 Velez Sarsfield
This tie is finely poised and the early stages of the contest will certainly be tight and cagey as both outfits get a feel for the game. With their away goal, Lanus have the advantage and will likely make life really difficult for Velez at La Fortaleza. We think Zubeldia's men will be heading for the final.