The Brazilian's South Korean team came from a goal down to beat Africa's TP Mazembe of the DC Congo 2-1 on Friday to qualify for a meeting with Estudiantes.
"We're going to face a team that's much more mature than ours with international experience. They are a team with great technical capacity," Farias said of the South American champions.
He added however at the post-match news conference that "football is technique and tactics but also surprise. (Estudiantes) must not think they'll have it easy against the Korean team they saw on the pitch today.
"There are plenty of examples of favourite teams that stumbled against technically inferior sides. I hope that at least we can reach the next stage," the 42-year-old Brazilian said.
Pohang were largely dominated by Mazembe in the first half of their quarter-final in which the teams' commitment to attack gave the match some atmosphere despite the 40,000-capacity Mohammed bin Zayed stadium being less than a quarter full.
Farias made some astute alterations in the second half that turned the match the Koreans' way and their Brazilian striker Denilson scored their goals and should have had a hat-trick.
Denilson, a much-travelled 33-year-old, made a dream start to the tournament in a place he calls a home from home having spent six years of his career in the United Arab Emirates.
"When a player feels good in a certain place, he's going to do better. I hope he continues to give himself and the team a favourable climate," added Farias.
Estudiantes, who like European champions Barcelona have a bye into the semi-finals, face Pohang on Tuesday in the 45,000-capacity stadium at Zayed Sports City on the city outskirts.
Mazembe's disappointed 59-year-old Italian-born French coach Diego Garzitto said: "We had got here very motivated. We must reflect on what happened today.
"The explanation is that we did nothing for 15 days after the (African champions) League ended before starting to prepare for this tournament. We arrived tired, lacking in fitness work.
"It was a very long season with more than 70 matches," added Garzitto, whose team now face the losers of Saturday's quarter-final between Atlante of Mexico and Auckland City of New Zealand for fifth place on Wednesday.
