It was misery for Leicester defender John Curtis who put a Gaizka Mendieta cross through his own net in the last minute, which saw Boro claim a point.
Boro had taken the lead in the first half through Juninho and should have sewn the game up on the stroke of half time, but Joseph-Desire Job saw his tame penalty saved.
However, the game transformed after the interval and Leicester dominated, with a brace from Paul Dickov and a late strike from Marcus Bent giving them a two-goal cushion.
Just when it looked as if Micky Adams's side had done enough, Massimo Maccarone hammered home and then Curtis deflected the ball past Ian Walker to make it all square.
The game started at a timid pace with both sides weighing each other up, but it was Boro who took the lead with a goal out of nothing after eight minutes.
Walker attempted a long clearance but the ball struck Job and rebounded for Juninho who took the ball on and finished into an empty net.
Boro then took control of the game and should have added to their lead, but Job and Stewart Downing both fired straight at Walker.
Just before the break Boro were then awarded a penalty after Nikos Dabizas climbed all over Job in the area, however the Cameroonian could not convert as he saw his effort easily palmed around the post.
Into the second period, Leicester levelled within four minutes and changed the whole course of the game.
The goal itself was controversial when a Steve Guppy corner was flicked on by Ricky Scimeca which in-turn went through James Scowcroft's legs - the ball then bounced up for Dickov, who finished past Mark Schwarzer - although television replays confirmed the Leicester striker used his hand to convert the chance.
Despite the questionable equaliser, The Foxes made sure it was of little consequence as they grabbed two more.
The second came after 65 minutes when Guppy's free kick was headed back across the six-yard box by Scimeca and an unmarked Dickov was there to bundle the ball past Schwarzer.
Boro were shell-shocked, but it got even worse less than ten minutes later when Schwarzer - making his 250th appearance - made a complete mess of a clearance to allow Leicester in.
Substitute Andrew Davies played a hard but straight ball back to the giant Aussie from 20 yards, but he took a touch to his right and could not reach it again - which allowed Bent to sneak in and fire into an empty net.
That was enough for most of the Boro faithful, who missed Massimo Maccarone firing home on the stroke of full time - which seemed unlikely to be anything other than a consolation.
Boro, though, saved their blushes to a certain extent as Scowcroft's wild clearance bounced to Mendieta who took the ball to the line and pulled back looking for Maccarone, but he found Curtis who obliged all the same.
Middlesbrough can consider themselves very lucky to grab a point and Leicester - who would have climbed out of the bottom three with a win - will be wondering how they did not claim victory.
