Cristiano Ronaldo has warned his Real Madrid teammates they will need to improve from their victory over Sporting CP to win the group.
Ronaldo's sublime free-kick against his boyhood club levelled the game late on for the hosts, before Alvaro Morata netted a dramatic winner in the fourth minute of injury time.
"This was a warning that we cannot be so soft or we'll be dominated," the Portuguese forward said after the match.
"We want to be first in the group, but Sporting played really well and made things tough for us.
"Instinctively I was going to celebrate it (his goal), but Sporting is the team that made me, and I couldn't do it.
"I want to finish here, in Madrid, it's where my heart is right now."