“Sporting revenge,” said Isco to reporters in Madrid after Wednesday’s game, “is a beautiful thing. Now we hope to knock them out.”

Isco is 21. Vengeance for him was personal and twofold, because Dortmund had not only knocked Real Madrid out of the Champions League last year, it also eliminated his previous club, Málaga. He is a player expected to mature into a vital No. 10 for Spain, though on Wednesday he stole in from the left flank to strike with a shot sweetly placed low beyond the reach of Dortmund goalkeeper Roman Weidenfeller.

Before that, the power and speed and cool finish of Bale picked holes in a Dortmund rearguard that appeared barely to have come out of the locker room. And when Ronaldo came through that same defense, too quick for Sokratis Papastathopoulos and Mats Hummels, his finishing stroke was full of the majesty that has decorated his career.

One hundred Champions League games and counting. Carlo Ancelotti, the Italian who specializes in guiding clubs to this trophy, cautioned that Real is still three games away from the final in May. The coach’s caution is no doubt born of the fact that his defenders showed complacency that would have been punished, had Lewandowski been present.

“We practically assisted two of their goals,” Klopp said after the game. “We had our chances in the second half, but we didn’t execute either the final pass or the attempt on goal. So we are not in a position to make battle cries about the return leg.”

Klopp spoke realistically about the obligation to throw everything at the game. He used the phrase “glimmer of hope.”

But his Dortmund is not the Dortmund of last year. The absentees cannot help, and even the fit players, such as that fine and spirited creator Marco Reus and the energetic Kevin Grosskreutz, appeared on Wednesday to be snatching at their half chances.