Arsenal have been forced to sit on their 3-0 defeat at the hands of Brighton since the beginning of the international break. That will potentially feel more frustrating than the result itself for Mikel Arteta, for his chance to respond has been delayed by as many as three weeks.

However, as humbling as that shock afternoon in Sussex was, it was also revealing for the champions. The rest of the Premier League discovered that this Arsenal side are not untouchable but, crucially, so did Arteta and his backroom staff.

It's begged questions about the January transfer window and whether the Gunners need to strengthen, having missed out on signing the star forward that they were searching for in the summer.

Those at the Emirates had their sights set on Morgan Rogers, Julian Alvarez, Vinicius Junior and others over the summer, but eventually failed to welcome any of their big name targets to boost their frontline.

The attention has since turned towards January, where interest in Real Madrid youngster Endrick could emerge alongside teammate Rodrygo.

But, as ever, Arteta also has his backline in mind. The Spaniard became a Premier League champion by creating the best defence in English football. That idea has not changed.

As much as a forward will likely take priority this winter, Arsenal also have their eye on Porto's Alberto Costa as they look to welcome another impressive right-back.

Arsenal dispatch scouts to track Costa

According to Caught Offside, Arsenal have dispatched scouts to complete in-person checks on Costa. They claim that the Gunners' interest is still very much at the scouting stage, but the right-back's €65m (£56m) release clause could quickly accelerate any potential deal.

Those in North London aren't the only ones interested, though. Manchester City, Manchester United and Paris Saint-Germain also have their sights set on the 22-year-old. Alas, Arsenal will hope the Premier League's guilty verdict against Man City will at least eliminate them as a transfer threat.

It's easy to see why there is such high-profile interest in Costa. The 6'1 right-back has shown plenty of potential at Porto and would slot right into Arteta's plans.

Compared to Arsenal's current fullbacks, it's clear that Costa would bring an added attacking threat. At Porto so far this season, the 22-year-old has created more than two more chances per 90 than Riccardo Calafiori and Ben White, whilst also recovering possession more.

In many ways, he is a modern day fullback full of energy. If Arsenal fail to improve their frontline in the natural way by welcoming a forward in January, then welcoming an attack-minded fullback wouldn't be a bad idea.

There's plenty for Arteta to think about ahead of the January window, especially as Costa continues to prove his worth in Portugal.