Sunderland's automatic promotion hopes were rocked on Saturday afternoon after they lost a remarkable nine-goal thriller against Coventry City.
The hosts had battled back on numerous occasions throughout the game but a litany of defensive errors saw them fall to their first home defeat of the season.
With Portsmouth and Barnsley both victorious in their games, it has piled on the pressure ahead of the final five games of the season.
The game had begun amidst a ferocious atmosphere, Coventry City bringing a sizeable following ad the Sunderland fans unveiling their new pre-match flag display.
With adrenaline high, the match was open and both sides begun with real intent.
The Black Cats stuck with their 4-4-2 shape from recent weeks and while they had some dangerous moments, it quickly became apparent that Coventry had the pace on the break to cause them real problems.
It had been a tight opening but the home side gifted away the initiative ten minutes in, a stray pass from Luke O'Nien falling straight to Wolves loanee Bright Enobakhare. His finish was composed, curled into the far corner.
Sunderland roared back into the game and it was 1-1 just minutes later, Coventry coughing up possession and allowing Bryan Oviedo to break. He found Lewis Morgan in space and the youngster went on a dazzling run, carrying the ball all way to the edge of the area. His unselfish pass found George Honeyman, whose effort was deflected into the bottom corner.
That sent the decibel levels soaring but a disastrous ten minute spell looked to have knocked all the enthusiasm out of Sunderland.
They fell behind again after more poor play in midfield, Luke Thomas driving into space and finding Amadou Bakayoko with a precise through ball, the striker easily scoring past Jon McLaughlin.
It was three when Coventry's runners again got in behind, this time left winger Jordy Hiwula finding himself in space. O'Nien recovered to try and block but his deflection left McLaughlin helpless and Sunderland with a mountain to climb.
They were being overwhelmed now, Enobakhare inches away from making it four when his effort drifted just wide of the post.
A good spell of possession was long overdue for the hosts and they were granted a lifeline as half time approached, goalkeeper Lee Burge dropping a cross from Oviedo despite being under no real pressure. Charlie Wyke, whose tenacity had been of the few positives in the half, was on hand to turn home the simplest of finishes.
He helped get his side level just before the break, battling for a cross that fell for Will Grigg. His first effort was blocked but the second was an easy finish into the bottom corner.
Jack Ross resisted the urge to shore things up during the interval, and though his side started the second half far livelier, the gremlins of the opening period returned to leave the Black Cats again chasing the game.
Possession was coughed up again in a dangerous area, Coventry quickly creating an overload on the break.
The ball fell for Jordan Shipley, who beat McLaughlin with a fine effort from the edge of the area.
Sunderland's promotion rivals were turning the screw elsewhere and with 25 minutes to go Ross rolled the dice, throwing on Aiden McGeady and Kazaiah Sterling.
The changes brought almost instant reward, McGeady cutting infield from the left and finding Wyke on the edge of the area. He did brilliantly to hold off his marker and tee up Power, whose effort from the edge of the area was deflected into the bottom corner.
The lead last less then ten minutes as yet more woeful defending blighted the home side.
Coventry created an overlap on the right and after Jack Baldwin failed to cut out a low cross, substitute Conor Chaplin, who had been on the pitch a matter of moments, was able to score.
Sunderland had fought back from the brink throughout the game but this last blow had a visibly draining effect.
They struggled to carve out any clear openings in the closing stages and the away side held out through eight minutes of stoppage time.
Sunderland XI: McLaughlin; O'Nien, Flanagan, Baldwin, Oviedo; Honeyman, Leadbitter (Sterling, 64) Power, Morgan (Kimpioka, 82); Grigg (McGeady, 64), Wyke
Subs: Ruiter, Cattermole, Dunne, Hume
Coventry City XI: Budge; Sterling, Davies, Hyam, Mason; Shipley, Kelly; Thomas (Wakefield, 76), Enobakhare (Chaplin, 76), Hiwula (Westbrooke, 89); Bakayoko
Subs: Brown, Ponticelli, Addai, Williams
Bookings: Sterling, 42 Leadbitter, 43 Chaplin, 79