Daryl Murphy’s brace at the City Ground looked set to see Blues move up to third in the table. The Republic of Ireland international sent Town on the way with a superb finish in the first-half and then headed home what looked like the winner 20 minutes from time after Robert Tesche had equalised for the home side.
From a late corner though Forest salvaged a point, Antonio heading home at the far post to keep their unbeaten record intact.
Town made one change from the side that drew at Sheffield Wednesday in midweek, Jonny Williams replacing Teddy Bishop in midfield, the Crystal Palace loanee having recovered from a groin injury.
Murphy forced Karl Darlow into the first action of the game, his header from a corner comfortably gathered by the Forest ‘keeper.
Town had an anxious moment at the other end when Britt Assombalonga got on the end of Chris Burke’s cross but he couldn’t get his shot in.
Forest went close moments later, Matty Fryatt heading against the post, then Town twice had chances to go ahead, David McGoldrick - up against his former club - was denied after good work by Tyrone Mings, then Murphy sent a right foot chance over the bar from a great position.
Christophe Berra headed wide from Williams’ free-kick as Blues threatened to break the deadlock, though Mings had to be alert to end the danger posed by Assombalonga.
That breakthrough came on 19 minutes, Cole Skuse found Murphy with a ball over the top and the frontman cut in on his left foot before bending the ball around Darlow and into the corner of the net.
Jonathan Parr lost the Forest defence with his run around the back but his header across goal from Mings’ cross was plucked out of the air by Darlow.
Conor Sammon robbed Jack Hunt but lost control of the ball as he raced into the box, both sides then forced into a change with Jamaal Lascelles replacing the injured Kelvin Wilson for the home side, Luke Hyam limping off seconds later, Jay Tabb on.
Luke Chambers’ hooked effort was dealt with by Darlow as Town looked the more likely to add to the scoreline, Williams then presented with a great chance after Forest lost possession deep in their own half but the Wales international couldn’t take advantage as Blues went into the break a goal up when maybe it should have been more.
Murphy was immediately in the action after the restart, his left foot effort sending Darlow scurrying across goal.
Chambers and Williams combined to stop Assombalonga inside the Town box, Williams then carving out an opportunity at the other end after linking up well with McGoldrick.
It took a terrific save from Dean Gerken to keep Blues in front on hour, the ‘keeper palming away Antonio’s close range effort and from the resultant corner, Sammon cleared off the line.
Forest were level though on 62 minutes, Tesche free at the far post to head home from Lansbury’s corner as the home side enjoyed their first real spell of attacking threat.
Antonio fired wide, Burke doing the same from the other flank before the home side were silenced again, Murphy thumping a header past Darlow from Mings’ cross on 71 minutes.
Darlow got down quickly to stop McGoldrick’s 25 yard strike finding the net but Forest looked certain to score seconds later, Antonio rounded Gerken but his effort was kicked off the line, then Assombalonga saw his follow up strike deflected behind by Gerken from six yards.
McGoldrick made way for Tommy Smith for the last 15 minutes, former Blue Dan Harding also joining the action for the home side.
Blues had an anxious look at the officials after Antonio went down in the box, the striker then firing high and wide from 20 yards as Forest pressed forward looking to salvage a point.
That equaliser came in added on time from Antonio’s header to deny Blues the win as Town went into the international break unbeaten in seven.