Marcelo lost Mane but I don't think you can blame him at all. He wasn't supposed to be marking him, he was supposed to be zonally marking the 6 yard. Pause it at 7 seconds here right when Ramos and Lovren contest for the ball. Firstly it's a nice little run by Lovren beforehand because he's completely free and can gets a big jump that I don't think he gets if someone's grappling with him. But if you pause at the moment where they go up for the ball you see everyone except Nacho and Marcelo are basically upfield of the Liverpool players because they expect Ramos to win that and they expect to be able to counter off it. Varane is moving away from the crowd as soon as he realises it's going over him, Cristiano and Benzema do the same. Marcelo's only near Mane because he smells danger and moves back.

Fully think it's Lovren who should get the lion's share of the credit for that, and maybe Casemiro for his movement - seems to try to move back to track Lovren but loses him and ends up ball watching instead of spotting the free man. But it's smart movement from Lovren and a great little run from Mane to get it over the line.