The Reds, who have endured a turbulent season on and off the pitch, beat Reading 3-2 at the weekend to go three points clear of the dropzone.
The victory at the City Ground over the Royals was only Warburton's second win in charge of Forest, since becoming their third boss of the season in March.
"The three points [against Reading] were the most important," Warburton told Sky Sports News. "The first hour or so we were very dominant and deserved to be in front against a talented Reading side, but we have to learn from the last 20-25 minutes. We let a good team like Reading play, conceded two late goals and put everyone on tenterhooks.
"The table doesn't lie at this stage of the season. We have the quality, nobody is doubting that, and we know how good they can be. We had good performances against Preston away and should have taken all three points, likewise against Derby, but we have to play well for 90 minutes, and turn these good performances into wins.
"We would be on 51 points [with victory at Queens Park Rangers on Saturday], and you'd like to think that was enough, but you can never be sure in football, and certainly not at this end of the table. In the last two games we just have to deliver two winning performances."
After the QPR fixture, Forest will end the season with a home game against Ipswich Town on May 7.