Thomas Frank was embarrassingly photographed carrying a coffee cup with Arsenal's badge on it just moments before Tottenham's Premier League clash with Bournemouth on Wednesday.
The Danish boss risked the fury of his own supporters as he emerged from the tunnel at the Vitality Stadium with an espresso cup showing the crest of Tottenham's bitter rivals shortly before kick-off.
In the picture which has now gone viral on social media, Frank can be seen grinning from ear to ear while making no attempt to hide the controversial item.
It appears a member of Arsenal's travelling squad left the cup in the away dressing room at the Vitality Stadium last weekend, either unintentionally or mischievously knowing that Spurs would be visiting just a few days later.
The Gunners sailed six points clear at the top of the Premier League by beating Bournemouth 3-2 on Saturday, courtesy of two goals from Declan Rice and one from Gabriel Magalhaes.
Frank took the cup to show his coaching staff before the match, appearing to see the funny side.
Tottenham have been on a disappointing run of late in the Premier League, having won just once in their last five games prior to Wednesday's clash with the Cherries.
Frank's side took the lead through Mathys Tel inside five minutes at the Vitality Stadium but found themselves behind at half time after goals from Evanilson and Eli Kroupi Junior.
Spurs thought they had rescued a point in the 78th minute through Joao Palhinha, before Antoine Semenyo netted deep into stoppage time to steal all three points for Andoni Iraola's side.
Tottenham, who have now picked up just two points from a possible nine in their last three games, slipped to 14th in the division after another worrying result for the Dane.
Kidso
41
Thomas is another manager trying to get himself sacked, as he knows Tottenham is a joke club
SonOfPep
19
That's Arsenal trophy
homdilpstz
10
Secret fan of our beautiful club
feuloprsuz
9
Does arsenal have cup 🤣🤣🤣🤣🤣