Rio de Janeiro, May 3 (IANS): Corinthians will need an early goal if they are to overturn a 0-1 deficit against Boca Juniors in their Copa Libertadores Round of 16 second leg May 15, said Brazilian football striker Alexandre Pato.

The defending champions must score twice and keep a clean sheet at the Pacaembu Stadium in Sao Paulo if they are to progress to the quarterfinals of South America's premier club competition, reports Xinhua.

"Unfortunately we weren't able to do what we hoped but we have managed to come away with a result that isn't so bad. Now we have to score an early goal and then try to score a second so that we can finish the game off," the former AC Milan striker said Thursday of his team's defeat at the Bombonera in Buenos Aires Wednesday.

Boca are likely to recall former Villarreal and Argentina international playmaker Juan Roman Riquelme for the clash after the 34-year-old missed the match with a thigh injury.

Pato, who joined Corinthians from AC Milan for a reported 15 million euros in January, is yet to rediscover his form after a series of injuries ravaged his final two seasons at San Siro.

He was introduced as a 75th-minute substitute by coach Tite, replacing young playmaker Romarinho.