Rio de Janeiro, May 2 (IANS): Flamengo cannot guarantee their passage to the Copa Libertadores knockout phase even with a home victory over Chile's Universidad Catolica on Wednesday.

The home side also needs fellow Brazilian team Atletico Paranaense to be lucky and avoid a home defeat to San Lorenzo of Argentina, also on Wednesday, reports Xinhua news agency.

"We have an obligation to win when we play at home," Flamengo coach Ze Ricardo told reporters on Monday.

"We know that our fans are going to support us. We need to find an equilibrium and have the patience to occupy spaces. Despite needing to win, we need to find a defensive balance because that could be the most defining characteristic," he added.

Flamengo are currently second in Group D with six points from four matches, a point behind Atletico Paranaense.

Ricardo's team could be without Romulo for Wednesday's match at the Maracana stadium after the former Brazil international midfielder twisted his right knee in the team's 1-0 victory over Fluminense in the first leg of the Carioca championship final on Sunday.

Doubt also surrounds Peru international striker Paolo Guerrero, who limped off in the second half of Sunday's match with a leg injury.

Medical staff have ruled out Argentinian center-back Alejandro Donatti due to a calf problem.