Arsene Wenger's miserable start to the new year took a turn for the worse as his Arsenal side - missing want-away forward Alexis Sanchez - lost 2-1 at struggling Bournemouth in a game he conceded they "had to win".
Hector Bellerin put Arsenal ahead shortly after half-time but Eddie Howe's side mounted an impressive comeback, scoring twice in five minutes through Callum Wilson and Jordon Ibe.
Defeat leaves Arsenal in sixth place, five points off the top four ahead of Liverpool's clash with Manchester City later on Sunday, and without a win in five games in all competitions while Bournemouth moved four points clear of the bottom three.
And while Wenger wrestles with problems on the field, the off-the-pitch saga involving Sanchez is adding to his concerns, with the manager acknowledging that continuing uncertainty surrounding the striker's future was the reason he was omitted.
"Half in half out, you never know this kind of situation during the transfer period," he said after the match. "That is why I decided to focus on the game."
Sanchez, who is in the final year of his contract, has been a long-term target for Manchester City and was expected to move to the Etihad Stadium in a £60 million (Dh302.4m) transfer on the final day of the last transfer window had Arsenal completed a deal for Monaco's Thomas Lemar.
City remained favourites to sign the Chile international this month until Manchester United expressed their interest last week.
The Old Trafford club's willingness to meet Arsenal’s £35m valuation of Sanchez, who can leave as a free agent at the end of the campaign, together with the possibility of offering one-time Arsenal target Henrikh Mkhitaryan as part of any deal, have increased the chance of the forward joining Jose Mourinho's squad.
But while Wenger confirmed he expected the situation to be resolved soon, he said he did not know what the final outcome would be.
Asked before the game if he expected Sanchez's future to be determined imminently, he said: "Yes. Don't read too much in it because even I don't know which way it will go."
Mesut Ozil was also missing for the Gunners after being ruled out with a swollen knee but Jack Wilshere started despite having limped out of the midweek League Cup draw at Chelsea with an ankle injury.
Wilshere was anxious to make a good impression on his return to the club where he spent last season on loan while Arsenal were keen to register their first victory since the turn of the year.
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Arsenal came close after eight minutes as wing-back Ainsley Maitland-Niles struck the bar with a curling shot. In the 35th minute, Danny Welbeck's shot was saved by keeper Asmir Begovic but if the Arsenal striker had gone to ground under the challenge of Simon Francis, he may well have won a penalty.
There was a much clearer claim for a spot-kick moments later in the Arsenal area when Alex Iwobi handled Ibe's free-kick but referee Kevin Friend decided the contact was unintentional.
Arsenal broke the deadlock seven minutes after the restart. Iwobi slotted an excellent pass inside left-back Charlie Daniels, allowing Bellerin to advance on Begovic before beating the keeper with a powerful angled shot.
Bournemouth forced their way back onto level terms with 20 minutes remaining after Ryan Fraser and whipped a low cross towards the penalty spot where Wilson nipped in ahead of keeper Petr Cech and turned the ball into an empty net with a first-time finish.
Four minutes later the home side went ahead as Wilson collected Lewis Cook's floated pass deep in the Arsenal area before laying off for Ibe to beat Cech with a low shot.