Defeat would have opened a seven-point gap between these high-fliers with just six games to go.
Although they scored first, Forest shaped their second half at not losing and City lacked just that little bit extra to break them down.
From the start the frenzied action matched the charged atmosphere with Kris Commons just missing the top right-hand corner with a 30-yard free-kick in the first minute.
Three minutes later he got in a low cross from the left and 3,300 visiting fans celebrated as Grant Holt steered a stooping header wide of keeper Adriano Basso.
The goal broke the tension and, with Bristol City chasing an equaliser, they had the better of the chances over the next half hour.
Their strikers Steve Brooker and Phil Jevons were given room in front of a solid back four to develop their attacks, but it was two defenders who crafted the leveller after 37 minutes.
Cole Skuse arrived in the box with a shot parried one-handed by Paul Smith and right-back Bradley Orr was on his shoulder to drive it back past the goalkeeper into the roof of the net.
City, who had won seven out of their last eight league matches, sensed they could build on this, while Forest's front pair of Grant Holt and Jack Lester were caught up in an increasingly niggly run-in with the home defenders.
Forest pushed many of their raids down the right where City's stand-in left-back Liam Fontaine was suspect.
But with no sign of breaking through, Forest changed their tactics early in the second half and put the emphasis on containment.