It had to go at some point but Southampton was an unlikely spot for Arsenal to finally see their lengthy 22-match unbeaten run ended on Sunday.
They may have ridden their luck at times but it was still an outstanding effort to put together a record like that. However, the defeat did shine a light on an existing problems.
Arsenal's defence has now conceded 23 goals which is more than Newcastle's and three times as many as leaders Liverpool.
Unai Emery's side also conceded twice against Spurs in the league game earlier this month but roared back in style to win 4-2.
That game is an obvious barometer to use for this quick re-match and, once more, Arsenal may need to have the shooting boots on as it's hard to see them keeping Spurs out.
Pochettino looking for statement win
The one big criticism of Mauricio Pochettino is that he's yet to deliver a trophy but Tottenham are still attacking on all fronts after somehow coming through their Champions League group when looking dead and buried after three games.
That 1-1 draw away to Barcelona was a huge boost and, although the home game with Burnley looked a case of after the lord mayor's show, Spurs still found a way.
Christian Eriksen's injury-time winner took Spurs to 39 points from 17 games - their best ever start to a Premier League season - in turn going five points clear of the Gunners.
Tottenham have been superb on the road this season with eight wins out of 10 in the Premier League, including a 3-0 triumph at Old Trafford.
That seemed like one of those season-defining away wins at the time but we now know that United are a pale shadow of what they once were. Given the context, victory here would feel more like the real deal.
The betting is tight but home advantage means Arsenal are slight favourites at 2.54 to get it done in 90 minutes.
Tottenham are 2.86 while The Draw in regulation time is 3.70.
To get to this stage, Arsenal have scored home wins over Brentford (3-1) and Blackpool (2-1) while Spurs have beaten Watford on penalties (2-2 in regulation time) at Wembley and seen off West Ham 3-1 at the London Stadium.
There's also a stat that Harry Kane hasn't played in this competition since 2015 although, now we're at the quarter-final stage and a trophy is up for grabs, the England striker will surely play some part.
Turning it up a notch surely applies to Arsenal too so it's fair to expect more regular first-teamers on both sides.
As is always the case in this tournament, though, it's understandable if you don't want to pull the trigger until the starting Xls are confirmed.
In terms of past history in this tournament, Arsenal have won seven, Tottenham three and there have been three draws. The Gunners won the last one in 2015/16.
90 minutes may not be sufficient
Arsenal have won their last six home games in all comps including that 4-2 success over their north London rivals, while Emery has a great record in Cup competitions, guiding Sevilla to three Europa Cup wins and winning both domestic trophies in his last two seasons at PSG.
Tottenham have just drawn away to Barcelona and already have eight road wins in the Premier League. They're desperate for a trophy and this is now an obvious chance.
Both sides have strong credentials and I can see the two needing penalties - they go straight to spot kicks after 90 minutes - to be separated.
Therefore, I'll go with the draw. A 0-0 looks unrealistic so I'll back 1-1 at 6.80 and 2-2 at 13.00.
BTTS hard to oppose
Surprisingly, three of the last four meetings between the two have featured a clean sheet so BTTS isn't a shoo-in when they meet.
Against that, Emery's side are set up for it to land and BTTS has been a winner for punters is nine of Arsenal's last 10 Premier League games.
It's very short though with Yes1.51. No is 2.46.
Team news needed for scorer punts
It's a dubious strategy having a pre-match goalscorer punt in EFL games until you've seen the teams so I can't get involved for now.
When known, beyond the obvious names there's a case for Henrik Mkhitaryan.
He's started both Arsenal's EFL fixtures this season and netted twice at Southampton.
Mkhitaryan is 11/4 (Sportsbook) to score anytime while, in the Same Game Multi market it's over 16/1 he fires home in a drawn game.
Arsenal are looking to reach the League Cup semi-finals in consecutive seasons for the first time since a run of three between 2005-06 and 2007-08.