In most people's eyes, Everton boss Ronald Koeman was the manager under the most pressure heading into the Premier League weekend.The Toffees lost 2-1 at home to Lyon in the Europa League on Thursday night, and after splashing the cash in the summer, have just two league wins to their name.If Koeman wasn't under intense scrutiny before Sunday's visit of Arsenal, he certainly is now, because his side were thumped 5-2 in embarrassing fashion on Merseyside.

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Wayne Rooney's stunner put Everton ahead, but goals from Nacho Monreal, Mesut Ozil, Alexandre Lacazette, Aaron Ramsey and Alexis Sanchez condemned them to a huge defeat.

As you can imagine, Everton fans were extremely disgruntled after their team's performance, but what their main sponsor tweeted after the match is sure to make matters a whole lot worse.

Everton's main sponsor angers fans with tweet

They may be represented by 'Angry Birds' on their sleeves, but Everton's main shirt sponsor for the 2017-18 campaign is SportPesa.

The sports betting platform also have a partnership with Arsenal, however they angered Everton supporters on Twitter with a post-match message they were forced to delete.

As you can see below, courtesy of ESPN's Mark Ogden, SportPesa's tweet showed nothing but pure delight for Arsene Wenger's men.

In fact, you would be forgiven for thinking they had no relationship with Everton whatsoever.

The tweet read: "Goals from 5 different players equals three points. Well in #Gunners! A superb gift by the players for the birthday gaffer! #MadeOfWinners."

Everton fans react on Twitter

Everton fans, who were understandably already in a bad mood, couldn't believe what their main sponsor had tweeted, and it didn't take long for them to share their opinions.

One supporter labelled SportPesa a "joke", while another called for all Evertonians to stop following a sponsor which clearly had "no clue".

Check out the best reaction below:

Having dropped into the Premier League relegation zone, Koeman's Everton need a drastic improvement to have any chance in next week's games against Chelsea and Leicester City.

What do YOU make of SportPesa's tweet after Everton 2-5 Arsenal? Be sure to have YOUR say in the comments box below!