Cristiano Ronaldo said Real Madrid's late escape act against Sporting Lisbon should serve as a warning after the European champions staged a remarkable four-minute turnaround to open their Champions League defence with a 2-1 win on Wednesday.
Ronaldo denied his boyhood club a famous win by cancelling out Bruno Cesar's opener with a free-kick in the 89th minute, before substitute Alvaro Morata continued Real's proud tradition of great European comebacks by grabbing a 93rd minute winner.
Despite a euphoric atmosphere at the Bernabeu Stadium at full time, Ronaldo issued a warning to his team mates.
"This is what Real Madrid is all about and comebacks like these form part of the mystique of this stadium - but this needs to be a warning for the future," Ronaldo told reporters.
"We can't be as soft as we were because teams will walk all over us. For me, Sporting's performance was not a surprise."
Ronaldo's rifled free-kick took his record tally of goals in the Champions League to 95, nine ahead of nearest challenger Lionel Messi, who hit a hat-trick in Barcelona's 7-0 drubbing of Celtic on Tuesday.
The Portugal captain, however, chose not to celebrate the goal, which was his third against his former club, adding to two he scored with Manchester United in two Champions League games in 2007.
"I couldn't celebrate it. This is the team that made me who I am and I have too much respect for them. They'll always be in my heart," he added.
Real coach Zinedine Zidane saluted the team's fighting spirit after they had looked on course to become the first defending European champions to lose their opening game of the following campaign since AC Milan in 1994.
"We're delighted because we believed we could turn it around right until the end and we didn't give up," Zidane said.
"Sometimes you meet opponents who play very well but our players were tremendous, they made an enormous effort and they got their reward."
Real Madrid (ESP) 2 (Ronaldo 89, Morata 90+5) Sporting Lisbon (POR) 1 (Cesar 48)