Arsenal are now three games deep into their pre-season campaign, even if supporters don't realise it.

The Gunners got their preparations for the new season underway early this month in something of a nothing game against Boreham Wood, with Arsenal running away convincing 8-0 victors.

Pierre-Emerick Aubameyang bagged a hat-trick at Meadow Park with Reiss Nelson, Alexandre Lacazette, Eddie Nketiah, Jeff Reine-Adelaide and Henrikh Mkhitaryan also scoring.

Unai Emery impressed Arsenal fans by sending the players who starred in first-half immediately back to the training ground for a light session.

It was a good exercise in terms of fitness and confidence but Gooners will get a much better impression of their new team as friendlies with Atletico Madrid, Chelsea and Paris Saint-Germain approach.

Arsenal's secret pre-season friendly

Arsenal are partaking in this year's instalment of the International Champions Cup with games in Singapore and Dublin.

A friendly with Lazio has also been pencilled in for August 4 in Stockholm, Sweden, just a week before the Premier League season kicks off.

However, one fixture that won't appear on the pre-season list is a game against fellow London side Brentford and it's already taken place.

Interesting details have now emerged

Rumours had been circulating that Arsenal had taken part in a behind-closed-doors friendly against the Bees before they fly out to Asia.

The match was believed to have been played on Thursday night, although little information about the fixture seemed to leak at the time.

Nevertheless, The Sun has disclosed some of the key details behind Arsenal's secret match.

The Premier League side tried to keep the game completely under wraps but were busted when a Brentford man posted about a pre-season friends and tagged 'London Colney' as the location.

It was later confirmed that match did take place, and the score? A 2-1 victory for Brentford.

That's not ideal for Arsenal to say the very least and worryingly, Brentford's winner came from a Bernd Leno mistake where he was rumoured to have badly fumbled a ball into the box.

Not the news you want to hear about your side's new goalkeeper, that's for sure.

On a positive note, however, there was another goal for Aubameyang who elevated his total to four goals in just two pre-season matches this summer.

It must be noted that Emery simply used the game for fitness reasons and to drill his philosophy into the Arsenal squad during match situations.

The result came just 24 hours after a similar match against Crawley, in which Arsenal claimed victory in a 9-0 thrashing per football.london.com.

Of course, only so much can be taken from a pre-season friendly but defeat to Championship opposition is certainly cause for disappointment.

That being said, it can only encourage Emery to make appropriate adjustments to Arsenal's preparations and ensure there is no such embarrassments in the games to come.

Even in just his first season at the club, there is great pressure on the new manager to bring about improvements and recoup Arsenal's Champions League spot.

Where do you think Arsenal will finish this season? Have your say in the comments section below.