GUADALAJARA, Jul 27 (SW) - A late penalty by goalkeeper Rogério Ceni gave São Paulo an away goal and a big advantage as they defeated Chivas 1-0 in the Copa Libertadores semi-final first leg at Estádio Jalisco.

Oswaldo Sánchez saved Chivas twice inside the sixth minute as he had to make two fine diving stops to deny both Leandro and Ricardo Oliveira, including the second which he pushed off of the post.

Three minutes later, Chivas' Omar Bravo smartly beat the offside trap on the left and then centered for Adolfo Bautista, but "El Bofo" turned and fired into traffic and it went by for a corner.

São Paulo's Oliveira thought he had headed home from a corner kick in the 18th minute, and the goal was initially awarded by referee Jorge Larrionda, but his assistant called him over and told him Oliveira handled.

Larrionda correctly heeded his linesman's advice and disallowed the goal. Replays showed the ball went off of Oliveira's arm before going off his head and into the goal, and Oliveira was booked for his protests.

São Paulo thoroughly controlled the first half of play and Danilo put a scare into Sánchez in the 40th minute with a shot from the edge of the area, but the Mexican number one was able to control.

Rogério Céni was at the top of his game in the 53rd minute when a free kick from the right was glanced on goal by Bautista, but the famous São Paulo goalkeeper never flinched and grabbed the ball.

Mexican forward Ramón Morales made São Paulo a bit nervous on 64 minutes when he hit a curling shot from the edge of the area, but the effort went wide of the goal.

Two minutes later on the other end, Danilo was able to get through and have a shot on goal from inside the area, but Sánchez got down low to make the save and preserve the 0-0 score.

Chivas were very unlucky in the 74th minute not to take the lead when a blistering shot from distance by Omar Esparza went crashing off of the crossbar with Rogério Céni helpless to stop it.

But 10 minutes later, São Paulo were awarded a penalty when subsitute striker Aloísio was tugged down in the area by Francisco Rodríguez, and Rogério Céni as cool as ever slotted home past Sánchez for a vital away goal.

The second leg will be in a week's time at Estádio Morumbi in Brazil with the reigning world champions firmly in control of the tie.