There was to be no great escape for Middlesbrough as a home draw with Aston Villa all but condemned Gareth Southgate's side to the drop.
Southgate was booed off the Riverside pitch at the end of tense affair where Boro gave everything but once more fell short.
Tuncay's glittering overhead strike combined with results elsewhere in the relegation battlefield had given Middlesbrough some hope.
But, in a 90 minutes that summed up their season, a failure to finish off a sluggish Villa side led to nervousness, panic and then the inevitable equaliser by John Carew.
Boro's predicament means they must now win their remaining fixture at West Ham - and hope Newcastle lose at Villa and Hull concede a hatful at home to champions Manchester United.
Stranger things have happened but a decade of Premier League football at the Riverside now looks at an end.
The fraying Premier League lifeline had unravelled for Boro even before kick-off after Jeremie Aliadiere failed to make the squad due to an ankle injury.
Yet Middlesbrough's urgency was evident from the opening seconds when Stewart Downing nearly contrived a goal, bursting into the box and cutting the ball back towards three red shirts but Gareth Barry's unflustered interception saved the visitors.
Tuncay flashed a header over the bar before Villa showed some quality with a neat build-up leading to Gabriel Agbonlahor trying to slide the ball under Brad Jones, who saved with his legs.