Karim Benzema rescued Madrid on Tuesday as Los Blancos rallied from behind to draw 1-1 at home to Chelsea in the opening leg of the semi-final tie in the Spanish capital.
Madrid made a sluggish start at Estadio Alfredo Di Stefano, where Thomas Tuchel's Chelsea led after 14 minutes thanks to Christian Pulisic, though Benzema restored parity 15 minutes later.
Zinedine Zidane's Madrid were unable to find a winner in a cagier second half and the Spanish powerhouse have now faced Chelsea more often than any other side in all competitions without winning in their entire history, failing to do so in four matches (D2 L2).
Reflecting on the match, Varane – who has been linked with a move to Los Blancos' Tuesday opponents – told Movistar: "I think we saw two games between the first half and the second.
"They started well with a lot of intensity and they pressed us well, and they broke our first line of the press with some very vertical play. With Karim's goal we got into the game and the second half was a lot better.
"We couldn't break their lines with our passing. Their press was annoying for us and we'll need to learn from the start of the game for the second leg."
Benzema once again showcased his importance to Madrid – the Frenchman drawing level with Raul as the joint-fourth leading scorer in Champions League history after netting his 71st goal.
Only Lionel Messi (36) and Cristiano Ronaldo (35) have scored against more different opponents in the Champions League than Benzema (33, level Raul).
Benzema, meanwhile, has scored six goals in this season's Champions League. In only one of his 16 seasons in the competition has he scored more (seven in 2011-12).
"In a game like this, Benzema makes the difference – he changed the dynamic of the game. We know his quality and he helps us a lot," Varane said.
"At this stage of the competition, our fitness will be important physically and also mentally. We need to go out to win the return leg."
Benzema's goal was Madrid's solitary shot on target against Chelsea. Only versus Paris Saint-Germain in September 2019 - when they had none - have they had fewer in a Champions League game since Opta began collecting such data in 2003-04.
Meanwhile, this was the only game in which Madrid have not scored at least two goals at home this season in Champions League. Still, they are the team who have scored the most home goals so far in the competition (14).
"We came in with a plan to do things and we couldn't do it," Marcelo told Movistar. "But when we started to do what we wanted, it was totally different.
"They run a lot, we knew it could happen, but there is another game as well. We know what we have to. It will be different at Stamford Bridge.
"We do not choose the rhythm of the game, we have to adapt to what there is. It was a difficult game, as they all are, but we are fine, we are calm because we are going to play a good game there [at Chelsea]."
"We left with our heads high. Now we are going to rest and see what we will have to do there, but it will surely change."