But Warburton also reiterated his message that belief remains the vital asset for his side, as they look to revive their Championship fortunes.
Forest played well for long spells against the Cottagers, creating numerous chances in front of goal.
While they went unconverted – beyond Daryl Murphy’s well-taken header at least – the Reds defensive fragility was again their undoing, as the London club took their own opportunities to secure a 3-1 win.
But as Forest prepare to face Sheffield United this weekend, Warburton believes his side have proved they are capable of playing good football and creating chances in the process.
“I have seen people saying ‘they cannot do it, they cannot play that way’ – they can. We saw them doing it against Fulham,” said Warburton.
“They can more than do it. They have the work ethic and character to go with it as well.
“They have shown they have the character as well, because they responded to going behind.
“When you ask about style of play, it does not happen overnight. You have to be brave and tell the players ‘this is how we are going to play’.
“You work with them to make sure they have the belief that they are good enough to do it – they are. They have shown that they are.
“But the belief is your strength. That message is only properly reinforced by getting your rewards, however.
“In the second half, if we had scored again, we would have won the game of football. I felt that. I felt our tempo and I felt our rhythm.
“But we came away with nothing again, which is the biggest frustration.”
Warburton makes no bones of the fact Forest simply must address their defensive malaise if they are to progress.
“We work every day on tightening things up, we train every day, offensively and defensively – we train in units and as a team,” he said.
“We have to look at the goals being given away. We cannot give free kicks away in that kind of area, against players of their quality.
“The foul can be on the halfway line. I am not going to condone giving fouls away – but maybe we are too honest and we need to be less naive and more ruthless at both ends of the pitch.
“There is no shortage of character, work ethic or commitment. But we want to see a reward for those qualities.”