They could have claimed all three points at the Lamb but Michael Brough missed a second-half penalty after Tamworth's Gavin McCallum had been sent off for bringing down Les Afful.
Taiwo Atieno had given lethargic Tamworth a 1-0 first half lead but the visitors responded after the break with a goal from Simon Clist.
Tamworth boss Mark Cooper made three changes to the side which suffered a 4-1 home reverse against Rushden on Tuesday night, drafting in long-term injury victims Michael Touhy, Alan Neilson and Joe Kendrick.
The Lambs also included former Scotland international Paul Devlin on the bench. He received international clearance from the FA to play on Friday after joining from Irish club Bohemians.
Forest Green manager Jim Harvey kept the same side which lost 1-0 at Weymouth in midweek.
Forest Green skipper Jamie Pitman fired an early shot wide for the visitors, who had not won on their travels for a year and were searching for their first win of the season.
The visitors started positively and Clist also struck a low shot wide on nine minutes.
Tamworth started sluggishly but took the lead on 12 minutes when Kendrick whipped in a corner and the unmarked Atieno powerfully headed home from six yards.
Forest Green began to probe for an equaliser and Allan Russell saw his low effort parried by Sean Bowles on 20 minutes.
The home side almost doubled their lead in freakish fashion on 22 minutes. Atieno charged down a clearance from goalkeeper Steve Williams and the ball hit the outside of the post.
The lively Atieno could have doubled the lead on 40 minutes after cleverly tricking his way into the box before scuffing his shot into the side-netting.
Tamworth failed to get going at the start of the second half and the visitors stunned their hosts with an equaliser on 47 minutes.
The lively Alex Meechan whipped in a cross from the right and Clist headed past goalkeeper Bowles who had committed himself by racing off the line.
The match took a dramatic turn on 50 minutes. McCallum was shown a straight card for bringing down the advancing Afful inside the penalty area.
The double punishment was a penalty but Brough hit a weak spot-kick which Bowles saved.
Rovers looked to make their extra man advantage count and Neilson had to make a timely challenge to deny Clist inside the penalty box.
The visitors were having plenty of possession and Russell fired wide as Rovers pressed for a winner.
Tamworth brought Devlin and Jon Stevenson into the fray in a bid to reverse their fortunes.
However, it was the visitors who continued to press and Kevin Nicholson saw a dipping shot go narrowly over the bar on 70 minutes.
The Lambs had their best opportunity on 83 minutes as Stevenson played a neat ball into the path of Steve Burton but the substitute lost control when well placed.
Charlie Griffin almost got his head to a deep cross from Paul Stonehouse as Rovers desperately sought a winner.
The home side almost produced a stunning finale as Graham Deakin fired in a powerful low shot but Williams pulled off a fine save.
Burton fired the rebound over but had already been penalised for offside.
Forest Green were also forced to play out the final minutes of the match with 10 men as Griffin was stretchered off. The lengthy stoppage resulted in nine minutes of added time.
The Lambs had strong appeals for a penalty turned down as Burton went down under a challenge from Christian Edwards.