Huddersfield 1-1 ForestForest:
Cox made no mistake when given a sight of goal but ultimately it proved to be a night of late disappointment for The Reds.
Keith Southern wasted a golden opportunity to give Huddersfield the lead when he lamely side-footed over after finding himself unmarked in the area from a corner.
Moloney and Blackstock combined again at the start of the second half; the Irishman powering into the area before finding the striker whose shot was deflected behind by desperate Town defending.
Another flowing move down the right hand almost reaped rich reward for Forest 12 minutes before the break. Moloney found Blackstock in space in the area and when his shot was cleared off the line by Jack Hunt, his follow effort was deflected just over the bar.
And the home ‘keeper came to his side’s rescue again midway through the first half, tipping over a spectacular volley from Adlene Guedioura after the Algerian midfielder had produced a piece of magic with his back to goal from outside the area.
That proved to be a brief respite for Huddersfield as Forest resumed their quest for an opening goal. A looping header from Blackstock enabled Cox to spring Town’s offside trap but the Republic of Ireland international was denied by the legs of Smithies.
A rare mistake by Greg Halford presented the home side with an opening. The former Sunderland and Portsmouth man misjudged the flight of Adam Clayton’s ball forward but Lee Novak spared his blushes by firing over the bar.
Sean Scannell gave Forest a scare as he rifled a drive from outside the area just inches over the top of Lee Camp’s bar, while at the other end Blackstock planted a header wide of Smithies’ right-hand upright from a teasing Andy Reid cross.
A mistake by Paul Dixon presented Blackstock with a sight of goal, albeit from an acute angle, but Huddersfield’s No.1 parried his shot.
But it was Lynch’s former team who flew out of the blocks and were denied a fourth minute breakthrough by the Huddersfield woodwork as Lewis McGugan hammered a 25-yard shot against the base of Smithies’ right hand upright after trading passes with Dexter Blackstock.
Huddersfield manager Simon Grayson included ex-Reds defender Joel Lynch a place in his team following his close season arrival in West Yorkshire.
The introduction of Cox – at the expense of Radi Majewski – was the only change boss O’Driscoll made to his starting line-up.
But when Adlene Guedioura and Lewis McGugan combined to present Cox with an opening he made no mistake, firing emphatically past Smithies from 10 yards out.
Forest had dominated for long periods up until that point but had been unable to find a route past Alex Smithies.
He sent all 2,274 of them into raptures with a 68th minute strike that bore all the hallmarks of a clinical finisher.
Cox had grown frustrated by lack of first team opportunities at his previous club but he wasted little time in making a big impression in front of the travelling Forest support.
Up until that point it had looked like being all about Cox as he wasted little time in making a big impression following his close season switch from West Brom.
But a rash challenge by Dan Harding on Jack Hunt in the third minute of added time presented Jordan Rhodes with the chance to level matters from the spot.
The Reds had appeared to be on course for a richly deserved three points when Simon Cox marked his full debut with the opening goal at the Galpharm Stadium.
Nottingham Forest were cruelly denied a second successive Championship victory by a last-gasp Huddersfield penalty. Camp, Moloney, Halford, Collins (c), Harding, Gillett, Guedioura, McGugan (Moussi 82'), Reid, Blackstock (Tudgay 75'), Cox (Hutchinson 89').
Subs: Evtimov (GK), McGoldrick, Miller, Majewski.
Scorer: Cox 68'
Bookings: Halford 51', Gillett 52', Hutchinson 90'
Huddersfield: Smithies, Dixon (Arfield 81'), Norwood, Clarke (c), Scannell, Clayton, Novak (Ward 81'), Rhodes, Southern, Hunt, Lynch.
Subs: Bennett (GK), Woods, Gerrard, Lee, Spencer.
Scorer: Rhodes (pen) 90'
Booking: Ward 87'
Attendance: 15,434 (Away: 2,274)
Referee: Neil Swarbrick