Midfielder Diego Galvan`s 14th-minute strike helped Argentinian side Estudiantes claim a narrow 1-0 victory in the first-leg of the Copa Libertadores' semi-final against Uruguayan outfit Nacional.

Galvan headed home Juan Sebastian Veron`s cross to give Estudiantes an early lead that they never relinquished, although Veron was replaced at half-time after the midfielder sustained a leg injury.

Santiago Garcia failed to convert Angel Morales` cross from close range shortly after the break while Nacional keeper Rodrigo Munoz denied Mauro Boselli shortly before the end when the striker was clean through on goal.

"We started slowly but I think this is a good result for us," said Uruguayan keeper Munoz.

"Now we have to fight in the second-leg."

The return encounter takes place next Wednesday at the Centenario Stadium in Montevideo.

In the other tie, Cruzeiro defeated fellow Brazilian side Gremio 3-1. The second-leg takes place next week in Porto Alegre.