Albert Adomah’s 32nd-minute winner was enough to secure three points in a 1-0 victory against Preston at the Riverside Stadium.
The Ghana international’s eighth goal of the season meant Boro climbed back to within a point of leaders Burnley and four clear of third-placed Brighton, who travel to Nottingham Forest tonight.
But Middlesbrough can climb to the top of the table by winning their game in hand against Reading tomorrow with a month remaining of the season.
Karanka said: “We don’t want to be in the Championship next season and at the beginning of the season the aim was to get in the play-offs.
“With the experience we have had from last season, now with six games to go, we are there because we are doing really well and it shows how good the players are.
“Now we have to forget the play-offs and promotion and just concentrate on the next game. Every point is gold and the key today was the crowd.
“Sometimes when you don’t feel their support you are going down but with them behind us the team is confident. We are more than together and that is the main thing.
“It is important to win at this time of the season.
Now we have our game in hand but we cannot think we have the three points in our pocket already.”
Middlesbrough: Konstantopoulos, Nsue, Ayala, Gibson, Friend, Forshaw, Leadbitter, Stuani (Downing 63), Ramirez (Clayton 69), Adomah, Nugent. Unused substitutes: De Laet, Rhodes, De Sart, Agazzi, Kalas.
Preston North End: Lindegaard, Vermijl, Wright, Huntington, Cunningham, Pearson (Welsh 62), Gallagher, Johnson, Robinson (Beckford 62), Doyle, Garner. Unused substitues: Kilkenny, Browne, Smith, Kirkland.
Referee: O Langford (W Midlands).