Arsenal's pre-season preparations ended in the worst way imaginable with a 1-0 North London derby defeat to Tottenham Hotspur on Sunday afternoon.

With home fans returning to the Tottenham Hotspur Stadium en masse, the Gunners were arguably the stronger team for the majority of the 90 minutes, but Son Heung-min netted the all-important winner for Nuno Espirito Santo's side in the 79th minute.

There was no love lost between the sides over the course of the afternoon - with five bookings being brandished out by referee David Coote - as Arsenal finalise their exhibition period with three defeats ahead of their Premier League opener with Brentford.

Here, Sports Mole examines three talking points from Arsenal's most recent derby defeat.

Defensive deficiencies

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In many ways, Sunday's defeat was a typical performance that we have become accustomed to from Arsenal. Dominate proceedings, fail to find the back of the net, lose when defensive deficiencies are exposed.

Ben White's hour on the pitch was an impressive one, with the Brighton & Hove Albion man not afraid to put his foot in when the ball was there to be won and progressing to the halfway line, but his centre-back partner Pablo Mari did not have an afternoon to remember.

Spurs experienced plenty of joy playing the ball over the top of Arsenal's high line, and for Son's winner in the 79th minute, Mari inexplicably fell to the ground while putting Japhet Tanganga under pressure, allowing the right-back to find his teammate for the winner.

Hector Bellerin certainly did not cover himself in glory during his time on the pitch as well, while Dele Alli hit the post twice and Bernd Leno had to deny Son from close range, so Gabriel Magalhaes's return from injury cannot come soon enough for Arsenal.

Assured performance from Albert

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With the luckless Thomas Partey expected to miss the rest of the month with the ankle injury he sustained against Chelsea, many Arsenal fans were expecting to see another uninspiring Granit Xhaka-Mohamed Elneny midfield pairing in North London.

However, Mikel Arteta threw a curveball by pairing Xhaka with new arrival Albert Sambi Lokonga, who did not produce anything spectacular but treated Gooners to a promising performance.

The former Anderlecht man ended the first 45 minutes having successfully completed 31 of his 32 passes - 14 of which came in Tottenham's half - while he also registered one tackle, one interception and won possession three times.

Whether Arteta will deem Lokonga ready for crunch matches against Chelsea and Manchester City is another question entirely, but the 21-year-old has surely put his name in the hat for a start at Brentford.

New striker needed?

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Emile Smith Rowe was trying to make things happen, while a returning 30-minute cameo for Bukayo Saka also showed the teenager's threatening capabilities, but the same old issues presented themselves for Arsenal's attacking line.

With Alexandre Lacazette leading the charge as Pierre-Emerick Aubameyang continued on the left, the former had three good opportunities in the first 45 but just could not make the net ripple, forcing a good save from Hugo Lloris and also striking the post with a curling effort.

Aubameyang's pre-season profligacy has been evident throughout the summer, and the Gunners captain swiped at thin air when trying to connect with Bellerin's deflected effort in the second 45, although the offside flag spared his blushes on that occasion.

The Gunners have already bolstered their defence and midfield this summer, but the forefront of the attack clearly needs addressing if Lacazette and Aubameyang fail to find their shooting boots. Amid links with the likes of Lautaro Martinez and Dusan Vlahovic, Arsenal have some major calls to make between now and the end of the month.