Colombia coach Jose Pekerman is yet to take a close look at round-of-16 opponents Uruguay, but knows a huge test awaits his team.
Pekerman was left delighted after seeing his team seal top spot in Group C with a 4-1 win over Japan at the FIFA World Cup on Tuesday.
The Argentina-born coach said Uruguay would be tough to overcome at the Estadio do Maracana on Saturday.
Oscar Tabarez's men could be without star striker Luis Suarez, who may be suspended after appearing to bite Italy defender Giorgio Chiellini on Tuesday.
"I haven't had a look at Uruguay yet because we were focused on this game but we know we're going to be taking on one of the strongest teams in South America and the world," Pekerman said.
"And (they have) some very experienced players who never know when they're beaten."
A brace from Jackson Martinez and goals from Juan Cuadrado and James Rodriguez saw Colombia maintain their perfect record.
Pekerman was predictably thrilled with his team's form.
"Obviously we're delighted. It was a very tough game for us today, just as we expected, but our confidence was high after our last two wins," he said.
"Everyone knows how we play and how we can play, because we showed that on the pitch.
"We've maintained our momentum in this group phase, scored goals and we've also overcome the obstacles put in front of us. We've also been successful at an individual level."
Martinez is confident his team can overcome Uruguay and said they knew just what they had to do.
"We've now got Uruguay in the last 16. It's not going to be easy at all but it's also true that we know each other well," he said.
"We know what we need to do and how we have to play that match."