Andre Schurrle's late equaliser helped Borussia Dortmund claim a 2-2 draw against Group F rivals Real Madrid at the Westfalenstadion.
Ronaldo grabbed his 95th Champions League goal when his first-time effort beat Dortmund goalkeeper Roman Burki to give the visitors a 1-0 lead, but Pierre-Emerick Aubameyang equalised just before half-time.
Raphael Varane restored Real's advantage in the second half but substitute Schurrle's late strike three minutes from time saw both sides share the spoils in an evenly contested encounter.
Madrid were looking for their first win in three games while Dortmund were riding on a four-game winning streak.
Ronaldo had the game's first effort on goal after three minutes as his free kick was saved by Burki before Gonzalo Castro stung the palms of Keylor Navas with a free kick of his own.
Madrid looked dangerous on the break and got their reward when the Portuguese forward put Zinedine Zidane's side in front after 17 minutes against the run of play. James Rodriguez played the ball forward to Gareth Bale on the right byline before the Welshman's back-heel across goal set up Ronaldo to fire home first-time.
Thomas Tuchel's side pushed forward in numbers as Madrid looked happy to sit back and defend their lead as Ousmane Dembele's effort looked goal-bound but Sergio Ramos' block saw the shot sky over the crossbar.
Sokratis Papastathopoulos almost levelled for the hosts as the Dortmund defender climbed above Ramos to meet Dembele's corner but Navas was able to punch clear.
Dortmund's pressure paid off minutes from the break as they scored a deserved equaliser. Raphael Guerrero's free kick was saved into the head of Aubameyang as the ball deflected off Varane towards goal before the Gabonese striker stabbed home from close range.
Navas was on hand to deny Aubameyang his seventh Champions League goal of the campaign as his curling strike was superbly saved by the Costa Rican goalkeeper shortly after half-time.
The visitors looked content with hitting Dortmund on the counter as Ronaldo's shot from distance deflected high and wide of Burki's goal. But Ronaldo would turn provider to restore Madrid's lead just after the hour mark.
The 31-year-old's corner found Karim Benzema, whose effort struck the woodwork before falling to his countryman Varane to score into an empty net.
Burki denied Ronaldo his 96th goal in the Champions League as his thumping effort from the edge of the box was tipped wide at the goalkeeper's near post.
Teenage duo Christian Pulisic and Emre Mor had chances to equalise in the last 10 minutes but Schurrle, who came on after 58 minutes, levelled late on.
The former Chelsea winger collected Pulisic's cross after Aubameyang's deflected overhead kick before his effort beat Navas at his near post to earn Dortmund a well-deserved point at home.