Real Madrid defender Raphael Varane says he and his teammates must learn from their mistakes after squandering a 2-0 lead to draw 3-3 at Legia Warsaw in the Champions League on Wednesday.
The Liga leaders looked set for all three points in Poland thanks to goals from Karim Benzema and Gareth Bale after 35 minutes.
However, the Polish champions hit back with goals from Vadis Odjidja-Ofoe, Miroslav Radovic and Thibault Moulin to take a 3-2 lead with seven minutes remaining before Real midfielder Mateo Kovacic equalised late on.
Varane, who started on Wednesday, told his club's official website: "It wasn't a good performance and we lacked intensity. It's a warning to us not to let our concentration and intensity levels drop. We need to improve in these areas because any team can create problems.
"We failed to perform better, both in defence and attack. We could have played better and played more of our game. Our best games come when we defend and attack together as a team."
Real coach Zinedine Zidane started with four forwards in Bale, Benzema, Cristiano Ronaldo and Alvaro Morata and it appeared to affect his team tactically.
"Playing with four forwards there's a different balance," the France international said. "We knew we'd have more space in behind and that we'd have to defend together but we didn't do that very well."
Varane says his team has room for improvement but must start to kill off games.
"We know what our strengths and weaknesses are and there's no need to panic but we must be aware that we've got things to work on," the 23-year-old said. "We're going to work hard, we'll put the effort in all together and at the same time be more clinical.
"We must use it to learn for the future."
Real are second in Group F, two points behind leaders Borussia Dortmund, who qualified for the round of 16 after their 1-0 home triumph over Sporting Lisbon on Wednesday. A point at Sporting Lisbon on Nov. 22 will see Real join Borussia in the next round.
Real resume La Liga action at home to Leganes on Sunday.