Brighton & Hove Albion and Chelsea shared the spoils for the first time in their collective history, as a Cesar Azpilicueta opener was cancelled out by Alireza Jahanbaksh's bicycle kick in the dying stages of the match.
The win takes the Seagulls to 24 points from 21 matches, while Chelsea just cannot kill games off against lesser daunting oppositions. Since the start of the festive period, they've succumbed to three defeats and a draw against teams outside the top half of the table - West Ham, Bournemouth, Southampton and now, Brighton.
The game was one of two halves, with the hosts taking the attack to Chelsea in the second. For the first time ever therefore, Brighton scraped anything against the Blues.
On that note, we analyse the major talking points from Chelsea's disappointing draw at the Amex stadium.
#1 Lampard sticks to four at the back, but changes personnel
In what turned out to be a masterstroke three GWs back at Tottenham, many assumed a 3-4-2-1 should be the best option for Lampard and Chelsea moving forward. However, a discernible lack of zip and permeability reduced the Blues to yet another defeat at the hands of a struggling team in the form of Southampton.
At Arsenal too, Emerson was sacrificed just after the half-hour mark in order to tweak the tactical setup, and so it paid off as Tammy Abraham clawed back all three points for his side with an 87th minute winner.
Lampard went with the more conventional, pacy approach that we know of his Chelsea side. Reece James was blooded into the team after suggestions that he'd be out for just under two weeks, while Kurt Zouma, Antonio Rudiger and Cesar Azpilicueta partnered him in the four-man back line.
Fikayo Tomori, who had a fine loan carousel at the Amex, couldn't find a place for himself in the starting XI.
Mateo Kovacic dropped to the bench while Jorginho started alongside N'Golo Kante. In front of them stood an effervescent Mason Mount.
Christian Pulisic, being another who was sidelined, returned to the wings for his first start in four games. Willian continued down the flanks, and so did Abraham.
#2 Brighton's set-piece frailties exposed as Azpilicueta scores
Chelsea began the game at a higher tempo, moving the ball about quickly and working together off it in order to create spaces and options for each other. Brighton meanwhile, struggled to take hold of their lines and in turn, awarded a lot of space for the likes of James and Mount.
Dan Burn, who walked off the pitch injured, couldn't quite get his geometrical and spacial positions right with respect to the way the midfielders provided cover.
The Seagulls, often astute with their set-piece procedures on either side of the pitch, failed to win both the first and second ball. Willian's well-taken corner was won by a leaping Zouma, who played it on for Abraham. There, if not for the first header, one simply shouldn't have allowed Abraham to drop in ahead and plant a shot.
Consequently, the strike was cleared off but straight to the Chelsea skipper, who treated himself with a tap-in. The visitors grew into the game on the same aspects, defending and communicating better at the back.
#3 James's inclusion leaves Brighton's shape in tatters
Reece James stole the show for Chelsea. He was combative, expressive and dynamic on both ends of the patch.
The full-back's inclusion was in fact, a great tactical move by Lampard to test Burn down that right-hand side. Burn, more known for his aerial and tackling ability, couldn't quite match the pace at which James was running inside the right, to the left of Lewis Dunk.
Not once or twice but thrice, the right back overlapped on the inside right and delivered teasing balls into the box. One of them was of course, the one that resulted in the goal-bound corner.
Defensively too, James was aggressive, decisive and apt. He chipped in with a number of vital challenges and well-timed tackles. Fair to say, Brighton hardly enjoyed anything down his end.
#4 Graham Potter ups the intensity with a change in dynamics
Desperate times call for desperate measures, and not for the first time this season, the former Swansea boss tinkered his configuration, fielding both Maupay and Connolly up front to thereby infuse energy, press the Chelsea defenders and run down the channels.
Aaron Mooy, who couldn't quite dictate the pace of play as he did against the Cherries, was soon substituted for Jahanbaksh.
They upped the ante, kept it alive and got thorough support from a rapturous home crowd. Credit Potter for dislodging his central midfield and stretching the Chelsea back line through a different medium.
Clearly then, there was a bit of urgency with respect to the way Brighton went about their game. They had more of the ball, more movement off it and a significant number of passes played through the midfield.
It certainly paid off, as Jahanbaksh plucked one out of thin air to claw Brighton back into it.
#5 Blues' ghosts come back to haunt them as Jahanbaksh nets
Before we get into the romantics of the otherworldly strike, let's discuss the horrendous piece of defending from Chelsea for the umpteenth time this season. They once again, couldn't hide their vulnerability from set pieces when the goal went in.
Against the out-swinging corner, it was imperative to go man to man and most importantly, save the second ball. That never happened, and somehow, the goalscorer was awarded way too much space inside the box with no one cashing in after the first header was won.
Then on, it was all about that strike.
It was a sensational bit of skill; to leap high enough, raise the left foot to provide leverage for the right to have a lash. And, how good was that finish? Kepa, who made a couple of remarkable saves to deny both the Brighton forwards, was simply rooted to his stance.