Mario Pineida's 80th-minute strike in Ecuador last week gave Independiente del Valle victory in the opening leg as Estudiantes struggled with the altitude in Sangolqui.
Estudiantes, who have won the Copa Libertadores four times, need to overcome Independiente del Valle to reach the group stage, as they aim to become the fourth club to claim five titles.
But Desabato does not want his team to be too focused on potential future glory ahead of Thursday's second leg at the Estadio Ciudad de La Plata.
"We have to improve a lot at home to reverse this," the 36-year-old defender told Estudiantes' website.
"In our house we have to win the game."
Only fellow Argentine clubs Independiente (seven) and Boca Juniors (six), plus Uruguay's Penarol (five), have won South America's premier continental club competition more than Estudiantes, who claimed their first championship in 1968 - the first of three in a row.
Estudiantes have not played in the Copa Libertadores since 2011, while they qualified for this year's competition via the 2014 Copa Sudamericana, where they reached the quarter-finals only to be eliminated by eventual champions River Plate.
With the Argentinian Primera Division yet to resume this year, Estudiantes are lacking match practice but should be fresh, while Independiente del Valle will have to recover from their Ecuadorian Primera A fixture against Deportivo Quito on Sunday.
Another Argentinian club Huracan look almost certain to progress to the group stage after thumping Alianza Lima 4-0 last week.
Huracan will host Alianza in the first match of the week on Tuesday, followed by The Strongest versus Morelia, who drew the opening leg in Mexico 1-1.
On Wednesday, Cerro Porteno will hope to build on momentum from last week when they welcome Deportivo Tachira to Paraguay.
While Cerro Porteno lost 2-1 in Venezuela, they scored the only goal of the second half thanks to Jonathan Fabbro and will hope that can inspire them at home.
Corinthians should progress after demolishing Once Caldas 4-0 last week, while Palestino will face a tougher task as they head to Uruguay to take on Nacional after winning their home leg in Chile by a solitary goal.
