It's unlikely that Arsenal boss Mikel Arteta will shed many tears over being dumped out of the Carabao Cup on Wednesday night.

The Gunners were defeated 3-1 by Brighton in what was a laboured display by a team who currently sit at the top of the Premier League.

It's not a competition that Arsenal will have held high in their list of priorities at the beginning of the campaign but there should be cause for concern after such a loss.

Indeed, it demonstrated again that their squad depth beyond their regular set of starters leaves a lot to be desired.

The north Londoners finished top of their Europa League group but it wasn't without a scare, as Arteta's men dropped three points against PSV Eindhoven.

On that night, the likes of Rob Holding, Fabio Vieira and Albert Sambi-Lokonga found life difficult.

That has been the story of the season so far, particularly for Lokonga, but Vieira's lack of form is now also becoming a worrying trend.

The Portuguese playmaker was signed from Porto in the summer and looked an underrated addition to the squad.

A fizzing goal against Brentford showed the immense quality in his locker but unfortunately, that's as good as it's got for the 22-year-old since arriving in England.

His performance against the Seagulls in midweek was again poor, with the Gunners succumbing to goals from Kaoru Mitoma, Tariq Lamptey and former Gunner Danny Welbeck who scored from the spot after debutant goalkeeper Karl Hein gave away a penalty.

The Estonian stopper, who became the first player from that nation to play for the club since Mart Poom in May 2007, was given a golden opportunity to prove himself but failed to take advantage.

Vieira, however, was equally as bad with the dynamic midfielder now making it nine successive matches without a goal contribution.

The youngster is still learning his trade and adjusting to English football so an element of patience must be applied to his displays.

That said, he needs to up his levels if he is to make an impression after the World Cup.

Vieira's display was best typified by Goal's Charles Watts who notably said he was having an "absolute howler" in the first half, with the attacking midfielder struggling to make an impression during his 72 minutes on the pitch.

Indeed, he lost the ball every 4.7 touches while just about seeing the ball more than the aforementioned Hein. Arsenal's stopper took 40 touches and played 22 accurate passes to Vieira's 43 and 27.

Considering he is meant to be the heartbeat of the team in his central role, it was a truly uninspiring set of numbers.

Furthermore, he made just one key pass and failed to accurately find a man with any of his three crosses. He made no notable defensive contributions, participating in just seven ground duels throughout the contest.

This was a night for Vieira to really prove himself to the manager but he spurned his opportunity and let his team down.