BUENOS AIRES, Aug. 8 (Xinhua) -- Juan Apaolaza and Gaston Campi struck first half goals as Argentina's Estudiantes beat defending champions Gremio 2-1 in the first leg of their Copa Libertadores round of 16 clash on Tuesday.

Apaolaza gave the hosts the lead at Estadio Centenario in greater Buenos Aires by curling a long-range effort into the top corner.

Campi doubled Estudiantes' lead with a downward header past Gremio goalkeeper Marcelo Grohe following a corner.

The Brazilian outfit pegged a goal back through Walter Kannemann, who nodded in from close range after Mariano Andujar parried away Marcelo Oliveira's glancing header.

Estudiantes were reduced to 10 men with 13 minutes remaining as Fernando Zuqui was shown a second yellow card for a rash challenge.

But Leandro Benitez's team held on to take an advantage into the second leg in Porto Alegre on August 28.