SAO PAULO, May 2 (Xinhua) -- Ronaldinho struck with a first-half header to help Atletico Mineiro defeat Sao Paulo 2-1 in their all-Brazilian Copa Libertadores round of 16 first leg on Thursday.

Jadson opened the scoring in the eighth minute at the Morumbi Stadium by slotting in a low shot after Paulo Henrique Ganso's clever layoff inside the area.

But the game changed in the 35th minute when former Brazil captain Lucio was sent off for a studs-up challenge on Bernard.

Ronaldinho put the visitors level on the stroke of half-time by nodding a Bernard corner-kick past veteran goalkeeper Rogerio Ceni.

One-time Brazil international striker Diego Tardelli then made it 2-1 on 59 minutes when he ran onto a long Marcos Rocha cross to slide in at the far post.

Atletico Mineiro will host the return leg in Belo Horizonte on May 8 with Sao Paulo needing at least three goals to advance to the quarterfinals.

"We came here respecting them because we know what they are capable of but we also backed ourselves and that showed," Ronaldinho said after the match. "It was a good result but there is still a game left and we know we have work ahead of us."