Chelsea will have to come behind to reach the Carabao Cup final after Championship side Middlesbrough stunned the blunt Blues with a hard-earned 1-0 win.
Hayden Hackney's first-half strike will separate the sides going into round two, having punished Chelsea for their poor finishing and in particular, Cole Palmer's hat-trick of sitters in the first 45 minutes. Boro boss and Manchester United great Michael Carrick - a man who's already won this trophy three times as a player - dealt with two early injury blows to get the better of Mauricio Pochettino, who knows even more so exactly what kind of player needs to be on his shopping list in the January transfer window.
Here are five talking points from a rocking Riverside.
Just seconds after referee Samuel Barrott blew his whistle amid the rapturous noise around the Riverside, the roof almost came off. Not, it wasn't because of any north-easterly gusts, but a mistake from Chelsea star Levi Colwill which put Middlesbrough striker Emmanuel Latte Lath through on goal.
Unfortunately for the Ivorian, his shot from the right-hand side of the penalty area was partially blocked by scampering Blues defender Axel Disasi. In his well-timed sliding challenge, Disasi caught Lath and left him in visible discomfort. And after receiving treatment and attempting to play on, Michael Carrick's joint-leading scorer had to come off in the fifth minute, replaced by fellow striker Josh Coburn.
Chelsea complete record-breaking Enzo Fernandez transfer after deadline day rush15 minutes later and Carrick - already dealing with key absentees - had to make his second change, as Chelsea winger Noni Madueke's foul led to an injury for Alex Bangura. The former Feyenoord prodigy also couldn't continue after the medical team came to his assistance, so Bangura was hauled off in place of centre-back Matthew Clarke, forcing Boro to reshuffle their defence, moving from 3-4-2-1 to 4-4-2.
Of all the players on the pitch, the experienced Jonny Howson would be among the last few you'd expect to misplace a pass in his own half on such a big occasion. But the former Leeds and Norwich midfielder, 35, did just that, handing Cole Palmer a golden opportunity to continue his goalscoring form.
Amazingly, though, the England international dragged his shot from inside D wide of the post, despite sending Middlesbrough goalkeeper Thomas Glover hopelessly diving the wrong way. Howson's blushes were spared and Palmer would soon regret his guilt-edged miss.
A long ball upfield found Boro wide man Isaiah Jones, who did well to cause problems for Colwill, cutting inside and ripping a low cross towards goal. 21-year-old Hayden Hackney, another Middlesbrough academy graduate, was speeding in and had a simple finish to beat Djordje Petrovic. Hackney's strike notably made him the first Boro player to score against Chelsea since Mark Viduka in 2006, coincidentally their last victory over the Blues.
Surely the next time Palmer got an opportunity he'd take it, right? For the Chelsea fans who'd made the 510-mile round trip, sadly not.
After Glover spilled a long-range shot from Enzo Fernandez right in front of the lurking Palmer and left his goal wide open, the Manchester City academy graduate somehow blazed his attempt over the bar. Then, in half-time stoppage-time, Palmer received a lovely through ball from Moises Caicedo and cut inside to give himself room for a shot.
Again, though, the £42.5million youngster fluffed his lines, firing a tame effort at Glover, who was left relieved once more. Simply put, Palmer should've had a first-half hat-trick.
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By this far, you probably get the picture: Chelsea are not clinical in front of goal. The Blues unsurprisingly dominated possession but despite all the talent on display and cute forward play, Mauricio Pochettino's men will have nothing to show for it coming home from the north east.
Middlesbrough, themselves struggling for goals of late, certainly had to battle to keep their clean sheet intact, but they must be expecting a much tougher task when they head down to West London. Pochettino has already signed Nicolas Jackson and Christopher Nkunku, but another striker in January wouldn't go amiss - even if Todd Boehly is finally trying to rein his spending in and close the revolving Stamford Bridge door.
Hakim Ziyech brutally denied deadline day transfer as PSG furious at ChelseaThese two will meet again at Stamford Bridge in a fortnight's time to decide who earns a place in the Wembley final on Sunday, February 25. Chelsea may be specialists in this competition over the past couple of decades, but it'll be Middlesbrough holding the cards in their second-leg clash after a tremendous display of attacking endeavour and defensive resilience to take the advantage.