Uruguay captain Paolo Montero is battling a stomach problem and could miss the semi-final of the Copa America football tournament against Brazil on Wednesday, coach Jorge Fossati said.

Montero, one of South American football's toughest defenders, sat out his team's quarter-final win against Paraguay because of a groin strain and is now undergoing treatment for gastritis.

"I won't rule him out yet because I want to see how he is on Tuesday, but he is the only player in doubt right now," Fossati said.

The 32-year-old, who plays his club football for Juventus in Italy, made his international comeback at the Copa America, two years after quitting the team at the end of the 2002 World Cup.

But Fossati said he did not expect Montero's absence to cause problems against Brazil, a match he did not see as any more difficult than Uruguay's group games against Argentina and Mexico.

"We are getting better, nothing marvellous, but better. Brazil has been playing pretty average until now. To say this is our toughest game would be to show a lack of respect for Mexico and Argentina," Fossati said.

Fossati is credited with ending Uruguay's dismal form in the World Cup qualifiers where they experimented with a risky attacking approach under eccentric former coach Juan Ramon Carrasco.

The team overcame Paraguay 3-1 in their quarter-final after drawing 2-2 with Mexico, beating Ecuador 2-1 and losing to Argentina 4-2 in the group stage.

Since Fossati took over, the team have returned to their traditional style of tactical discipline and gamesmanship.

Fossati said recently that one of the main reasons for recent defeats was that Uruguay failed to pick up enough yellow cards.