The centre-back had raised hopes that Arsenal were ready to turn the Bavarians over in Munich but after a 5-1 loss he was left with egg on his face
Per Mertesacker will surely never use Twitter on the same day of a game ever again.
The Arsenal centre-back will have been scarred by the responses after his pre-match update on social media backfired quite spectacularly.
The German, who hasn't featured for the Gunners since way back in April 2016, was undoubtedly expecting big things from his side at the Allianz Arena as they prepared for Wednesday's Champions League clash.
In the build-up to the game, Mertesacker tweeted a preview image with the accompanying text: "We mean business tonight!"
Quite the opposite ultimately occurred on a dismal night in Munich for the Gunners, however, with Carlo Ancelotti's side running riot and claiming an emphatic 5-1 win.
The north Londoners are now facing up to the very likely prospect that they will be elimated from the last 16 of Europe's premier club competition for the seventh season in a row.
And Gunners fans were quick to jump on Mertesacker's unfortunate tweet after the game, with one fan even predicting that the hosts would go on to score five...
@mertesacker This is gonna bang when they put 5 past us...— Hafiz (@HafizRahman100) February 15, 2017
@mertesacker That tweet will look embarrassing when we get thrashed!— Lukas (@_lukasjohansson) February 15, 2017
@mertesacker why can i see this coming back to bite us?— Rob Ashdown (@RobLad1985) February 15, 2017
@mertesacker oh for Christ sake Per.— Luke Whitworth (@LWhitworth7) February 15, 2017
@mertesacker this is awkward— jordan durrans (@jdurrans1995) February 16, 2017
Arsenal now head to non-league side Sutton United in the FA Cup on Monday as they look to recover from the humbling at the hands of the Bundesliga giants.
They then travel to Anfield to face Liverpool in the Premier League before the return leg against Bayern on March 7.