Arsenal blew the chance to clinch a top-four finish in Tottenham's backyard as Mikel Arteta's side slumped to a demoralising 3-0 defeat in the north London derby.
Harry Kane fired Spurs into the lead from the penalty spot in the 22nd minute and things went from bad to worse for the Gunners just 10 minutes later when Rob Holding was dismissed for a second bookable offence. Kane compounded Arsenal's misery by bagging a second minutes after Holding's dismissal before Son Heung-Min netted a a third almost instantly after the break to cap a rotten night for Arsenal, who now sit just a solitary point above Antonio Conte's side.
Regardless of whether or not the Gunners are able to regroup and pinch the final Champions League spot ahead of their rivals in the dying embers of the season, Arteta is expected to be a busy man in the summer transfer window. Here, Mirror Football takes a look at where Arsenal could do with strengthening ahead of next season...
Centre-back
Ben White has made a huge impact at the Emirates since his £50million move from Brighton in the summer - how the Gunners missed him at the Tottenham Hotspur Stadium, as a meltdown from Holding left Arsenal's top-four hopes hanging in the balance.
With White only fit enough for the bench, Holding was drafted in to partner Gabriel Magalhaes, but he was an accident waiting to happen from the start. The ex-Bolton man was given his marching orders after picking up two cautions in seven minutes to leave Arsenal with a mountain to climb.
If Arsenal have ambitions of staying in and around the upper echelons of the Premier League, then they need an upgrade on Holding. William Saliba is due to return to the Emirates in the summer after another impressive spell away on loan and, based on this evidence, he has to be ahead of Holding in the pecking order next year.
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Left-back
For the second consecutive match, Arteta decided to snub Nuno Tavares and instead deploy Takehiro Tomiyasu in an unfamiliar left-back role. Tavares only arrived at the Emirates last summer to provide competition for Kieran Tierney, but already the £7million man's spot in the Arsenal team appears to be at risk.
The 22-year-old has produced some erratic displays and already dropped some major clangers during his maiden season in the Premier League. And with Tierney plagued by injuries this term, it's hard to see Arsenal heading into next season without adding another left-back to their ranks.
Bologna starlet Aaron Hickey has been linked with a £17m move to north London after a stunning season in Italy. The 19-year-old looks the part and would represent a more defensively sound option than Tavares as a deputy for Tierney.
Right-back
Cedric was given the nod at right-back to accommodate for Tomiyasu being nudged over to the opposite flank. And while Arsenal's recent revival has been spearheaded by a host of forgotten men, Cedric was another fringe player who let the Gunners down with his needless barge on Son in the box.
The ex-Southampton man has been a semi-regular in recent weeks as a result of Tomiyasu being sidelined, but he isn't up to scratch to feature regularly for the Londoners; even as an understudy.
Arsenal continued to be linked with a host of right-backs after signing Tomiyasu last summer, including Brighton starlet Tariq Lamptey. Tomiyasu is a far more conservative player than Lamptey, but a more explosive option like the ex-Chelsea man would mesh will with the steel of Tomiyasu.
Striker
Eddie Nketiah has been doing a fine job for Arsenal in recent works, but it's common knowledge that the Gunners need to address their dearth of striking options in the summer.
Nketiah was pretty much consigned to a spectator role after Holding's silly dismissal, but the 22-year-old's recent displays merit a spot in Arsenal's plans next year. However, the Hale End graduate isn't going to head into next term as the Gunners main man.
Gabriel Jesus is an established Premier League striker and has been mooted as a potential summer target for Arsenal. The 25-year-old has only failed to hit double figures in one of of his six seasons at Manchester City and would thrive as the main man at the Emirates.
With Alexandre Lacazette also poised to leave the Emirates, Arsenal would need more than Jesus and Nketiah alone to challenge domestically and in Europe. But the Gunners should prioritise a summer deal for the Brazilian poacher if they are serious about sustaining the progress they've made this season.