Goals from Benni McCarthy and Jason Roberts looked to have secured three precious points for bottom-of-the-table Blackburn, but substitute Daniel Sturridge scored one and then set up Robinho's equaliser in the last minute of the game.
That's now three games unbeaten for new Blackburn boss Sam Allardyce, but the sequence would seem scant reward for his side, who created countless chances and took a two-goal lead in the 84th minute of the game.
For Hughes, however, who led Blackburn to three successive top-flight finishes before moving to Eastlands in the summer, inconsistency continues to prove costly, with his side winning just two of their last 11 league games.
Before kick-off, both sides were forced to make a change apiece from their last outings, with Tugay replacing the injured David Dunn for the hosts and Nedum Onuoha coming in for Micah Ricahrds, who was only fit enough to claim a place on the Manchester City bench.
In bitterly cold conditions, both sides started brightly, with the visitors close to taking the lead with less than two minutes on the clock. Michael Ball swung in a corner from the right, Vincent Kompany headed down, but Felipe Caicedo - who scored twice in City's Boxing Day blitz at home to Hull - fired over at full stretch.
Straight up the other end, Roberts was brought down by Richard Dunne on the edge of the area and Brett Emerton's free-kick appeared to strike Stephen Ireland's arm inside the box.
City had appeals for a penalty themselves moments later when Robinho claimed he was clipped by Andre Ooijer, but again referee Howard Webb remained unmoved.
Robinho, who also bagged a brace during the week, ought to have grabbed his third goal in as many days when Caicedo put a cross for him on a plate, but the unmarked Brazilian somehow headed wide.
On 25 minutes, Morten Gamst Pedersen picked out Roberts with a ball over the top, but after turning brilliantly inside Onuoha, the former Grenada international was denied by Dunne's great goal-saving tackle.
Less than 60 seconds later, City too opted for the direct approach, as Kompany's quick free-kick spotted the run of Caicedo, but Paul Robinson came rushing out of his goal to Rovers' rescue.
After such an open 45 minutes of football, it was only a matter of time before the deadlock was broken and the home side duly obliged right on the stroke of half-time.
Emerton's cross found its way through to Roberts, who spun superbly past two City defenders, leaving space for McCarthy to coolly slot the ball into the bottom corner of the net.
Rovers started the second half in much the same vein as they had ended the first, with Emerton firing high over the bar less than a minute in, before Ooijer ended a well-worked move which he had started himself with a shot straight into the arms of Joe Hart.
The visitors weren't without their chances however, with two falling in the space of a minute. From Elano's pin-point cross, Shaun Wright-Phillips' backwards header bounced back off the post and Ireland curled an effort inches wide of the far post on the follow-up.
Hughes used up all three subs as he sought a route back into the game, but it was the home side who thought they'd wrapped it up with their second of the game. On 84 minutes, Ooijer's free-kick was flicked to the back post by Samba and man-of-the-match Roberts headed past Hart into the top corner of the net.
But City refused to give up and reduced the arrears just four minutes later. After some fancy footwork by Robinho on the edge of the Rovers' box, his chip was only half headed clear by Ooijer and super sub Sturridge volleyed home.
And in the fourth and final minute of time added on, the skilful City striker skipped past two Rovers challenges before playing in the unmarked Robinho on the far side and the Brazilian bagged his 12th of the season with a neat finish under Robinson.