Middlesbrough sank deeper into crisis in the absence of manager Aitor Karanka as the promotion hopefuls suffered a 2-0 defeat at lowly Charlton.
The visitors were still in a state of confusion after their Spanish boss did not travel with the squad, with assistant Steve Agnew taking charge at the Valley, and goals from Jorge Teixeira and Callum Harriott added to Middlesbrough’s problems.
Karanka walked out following a stormy meeting with his players on Friday, and despite later seeking to apologise he did not make the trip to London for the Sky Bet Championship clash.
With the game held up 30 seconds after kick-off due to a large number of beach balls thrown onto the field by protesting home fans, unhappy with their own situation, the contest began in scrappy fashion.
The first real effort of note came after 24 minutes, when Charlton winger Johann Gudmundsson unleashed a fierce drive from just outside the area, which was well held by Middlesbrough hoalkeeper Dimi Konstantopoulos.
The visitors looked more assured initially and had the bulk of possession. However, another chance fell to the hosts, this time after 39 minutes, when Harriott blasted his shot wide from the edge of the area after some good movement.
Middlesbrough almost took the lead in first-half injury time, albeit with help from Charlton defender Rod Fanni, who nearly put a clearance into his own net. Goalkeeper Nick Pope showed excellent reflexes.
The second half started evenly, although home captain Jordan Cousins had the first effort of the half after 54 minutes. His solo run from just inside the box was unchallenged and led him to try his luck from 20 yards, with a shot that went well over the bar.
The deadlock was finally broken after 57 minutes as Teixeira headed home from a corner by Gudmundsson - his first goal for the club.
Middlesbrough, who had begun to look lacklustre, finally showed some endeavour, and Albert Adomah forced Pope into palming away his shot after 70 minutes, before blasting a rebound over the bar.
Gaston Ramirez also forced Pope into tipping over the bar, from a free-kick after 72 minutes.
Charlton doubled their lead with 10 minutes remaining, when a shot from Harriott rebounded off defender Dael Fry, the persistence of the forward paying off after he pounced on the loose ball to blast home past Konstantopoulos.
The only on-field negative for the hosts came with an injury to Harriott after 88 minutes, with the goalscorer limping off. Problems are suddenly abundant for second-placed Middlesbrough at this critical stage of the season.