The Portugal international vowed to "fight until the end", after falling eight points behind arch-rivals Barcelona, after just four games of the new Liga season.
Nevertheless, the 29-year-old rued the lack of defensive concentration which led to Piotr Trochowski's second-minute opener, but insisted attention now turns to the Champions League clash against Manchester City on Tuesday.
"We will fight until the end, [it] is the motto of Real Madrid," he was quoted as saying by Canal+.
"Eight points is difficult, but the most important thing is to know that the group has worked hard. Trochowski's goal made things difficult.
"We have to fight to the end, now we have to think of City. I think we were always in control. Again, we suffered from goal-kicks, which hampered our work later. We had a lot of ball possession, but they defended well and [conceded] no clear chances.
Jose Mourinho's men welcome the Premier League champions to the Santiago Bernabeu on Tuesday and kick-off is at 18:45 UTC.