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.
