(Reuters) - Colombia coach Jose Pekerman expects his unbeaten team to be tough opponents for Uruguay in the World Cup's first knockout round, he said on Tuesday.

Pekerman, a man of few emotions, took time to savor his side's three wins and nine points to top Group C, a result few expected from the South Americans two weeks ago.

"Managing to win three games makes us trust ourselves even more," the Argentine coach told reporters after a 4-1 hammering of Japan, who are heading home.

"We feel really confident. We have proved once again that Colombia are a very tight team.

"We think we will be difficult opponents for Uruguay," he told news conference.

Pekerman, who used to play in Colombia, took over the "Cafeteros" in 2012 and has taken them to their first World Cup finals since 1998.

Minutes after the match at the Pantanal arena, the coach said he had scarcely had time to think about the game against Uruguay on Saturday in Rio de Janeiro's Maracana stadium, where the tiny Latin American nation famously beat Brazil to win the World Cup in 1950.

But he knows from experience not to be too confident, even though Uruguay struggled to qualify for the last 16 after an initial loss to surprise Group D winners Costa Rica.

"We will face one of the biggest teams in South America and the world," said Pekerman, who coached Argentina at the 2006 World Cup.

"They have history and great players and experience and they never give up. They are very consistent, strong and with a lot of experience."

Pekerman trod cautiously when asked about the prospect of Uruguay playing without leading striker Luis Suarez, who may face suspension for biting an Italian player on Tuesday.

"We still don't know what has happened today," he said. "We'll see."