Neil Warnock blasted the assistant referee after Shaun Wright-Phillips' effort was ruled out for offside in the draw against West Brom.
Heidar Helguson notched his sixth goal of the term as he headed home Joey Barton's chipped cross at the back post after 20 minutes.
But the turning point came just minutes later when diminutive winger Wright-Phillips fired home a stunning volley, which replays showed should have counted.
Yet Rangers will ultimately have themselves to blame for the draw as Wright-Phillips and Rangers skipper Joey Barton missed inviting chances at add the second goal before Shane Long's late leveller.
"I was disappointed, [we were] winning 1-0 and Shaun Wright-Phillips scores a cracking goal - and it's not offside," Warnock told Sky Sports.
"I'm so disappointed in the linesman there, and you would expect them to get them right when they are in line.
"But we still should have won, we had loads of opportunities, we just couldn't take the second goal and then they break away. I thought it was a goal that could have been prevented.
"But that's how it goes. We came in almost thinking that we've lost the game, but really I thought we were different class today.
"I thought the lads were fantastic, they played some fabulous football.
"I thought Joey and Faurlin in midfield were excellent, as were the front lads and the back lads were solid. I thought was a great team performance."
Baggies substitute Peter Odemwingie created the equaliser as raced down the left touchline and centred for Long who snared the late goal.
It was salt in the wounds for Warnock who was still bristling at the thought of the assistant referee disallowing the goal.
"I'm just disappointed in the linesman," he added. "I thought Martin [Atkinson] ran the game lovely, I mean he didn't have much to do really.
"It was a super game to watch and referee, really straight forward, I'm just really disappointed that you get a crucial decision like Shaun Wright-Phillips' and you get conned by a 'Tony Adams'.
"That's what Tony Adams used to do, run out and then plead with the linesman to give offside. He's in a great position and he's right across it - he's onside.
"It's a cracking goal so yes we are gutted. I just wonder how they feel when they feel when they watch mistakes like that at night time."