Gareth Bale put Madrid on course for their first win at the seventh attempt in Dortmund with a brilliant volley into the top far corner early in the first half.
Ronaldo's return sparks Real Madrid victory at Borussia Dortmund
A double from Cristiano Ronaldo helped two-time defending champion Real Madrid to a 3-1 win at Borussia Dortmund in the Uefa Champions League on Tuesday.
Ronaldo, yet to score in the Spanish league where he sat out a five-game suspension for shoving a referee, took his tally in Europe's premier competition this season to four goals in two games as he sent Dortmund to its second straight defeat in Group H.
Tottenham, which beat the German side in their game at Wembley Stadium, defeated Apoel Nicosia 3-0 away thanks to a Harry Kane hat trick in the other group game.
Gareth Bale put Madrid on course for its first win at the seventh attempt in Dortmund with a brilliant volley into the top far corner early in the first half, and then ran onto Toni Kroos' forward ball before crossing for Ronaldo to score early in the second.
Pierre-Emerick Aubameyang pulled one back almost straight away for Dortmund, but Ronaldo sealed the win late with a thumping finish to beat Roman Buerki at his near post.
"We could have scored more. We had chances. The important thing is to score more than our opponents and we did that," Madrid coach Zinedine Zidane said.
Buerki was by far the busier goalkeeper as Madrid made a better start. Dani Carvajal forced him into a good save early on before Lukasz Piszczek had to slide in to deny Bale what looked a certain goal.
Living dangerously at the back, Dortmund opted to push forward. Andriy Yarmolenko almost found Aubameyang before Maximilian Philipp's goal-ward effort was scrambled away between goalkeeper Kaylor Navas and Sergio Ramos. The ball touched Ramos' hand from Navas' deflection but the officials felt it was unintentional.
"These are key moments that could lead to a different result," said Dortmund midfielder Nuri Sahin after facing his former side. "Still, you have to say Madrid were good."
The visitors went ahead when Carvajal sent a cross for a Bale to stroke nonchalantly inside the far corner with the inside of his left boot.
Buerki denied the Welsh forward another, and Carvajal got back with a timely clearance to stop Aubameyang at the other end.
Ramos missed a good chance with a header from a corner before the break, and Dortmund emerged with intent after it, when Raphael Varane got back with a vital goal-line clearance to deny Aubameyang again.
Then Madrid scored again. Kroos played a perfect through ball for Bale, who took one look and delivered a perfect cross for Ronaldo to score from close range.
Aubameyang got ahead of Ramos to pull one back five minutes later, but Ronaldo had the final say, again. It was his 14th goal in his last seven games in the competition.
Dortmund, which has made its joint-best ever start to the Bundesliga, already faces the prospect of a first-round exit.
"It wasn't easy to play our system at this level, to enforce our way of playing, pressing high up the pitch, against the top favorites," Sahin said. "They played well. They have good footballers in their ranks. They dominated the center with Isco and four midfielders. So it's not easy. But that's the development we have to make."