Pep Guardiola says "this isn't over" despite Barcelona holding a 5-1 first-leg lead over Shakhtar Donetsk in the Champions League.
Andres Iniesta, Dani Alves, Gerard Pique, Seydou Keita and Xavi were the goalscorers for Barca while Shakhtar's reply came from a Yaroslav Rakitskiy strike when they were already 3-0 down in the quarter-final clash.
Barca are now overwhelming favourites to progress through and, barring a huge upset in both games, in the semi-finals will meet arch rivals Real Madrid, who boast a 4-0 lead over Tottenham following their quarter-final first leg.
If that does happen, then Barca and Madrid will face each other four times in a matter of weeks as they also have a league encounter and the Copa del Rey final to contest.
Shakhtar coach Mircea Lucescu admitted after the match that he thought the semi-finals were now beyond his side, saying: "I think the tie is already decided and they are going through."
However, Guardiola, whose team were fortunate to only concede once against a Shakhtar side that created several good chances and who are very strong at home, is preaching caution.
He said: "I'm more than happy but I'm aware that this isn't over. We must take things very seriously. Shakhtar are one of the best teams I've ever seen."
Guardiola highlighted his side's recent Copa del Rey quarter-final against Real Betis as a reason not to get carried away.
In that tie Barca recorded a 5-0 win in the first leg but had a nervous time of it in the return meeting as they found themselves 2-0 down after seven minutes and 3-1 down at half-time.
Betis could not make any further inroads in the second half and Barca would end up reaching this month's final after knocking out Almeria in the semis, but the memory is fresh in Guardiola's mind.
"We still remember the 5-0 against Betis and how bad we had it there in the cup," he said.
Barca midfielder Iniesta, who celebrated the birth of his baby at the weekend by opening the scoring inside two minutes against Shakhtar, also refused to assume a semi-final place was now theirs.
He said on his club's website: "We would be wrong if we thought that it was already done.
"I think everybody has seen the opportunities Shakhtar had. They created a lot of chances, they've hit the post, they had a one-on-one. In the return match we have to be careful."