A stoppage-time winner from Chemsdine Talbi saw Sunderland come from a goal down to defeat Chelsea 2-1.
Enzo Maresca's side made the perfect start after just four minutes when a fast-flowing move resulted in Alejandro Garnacho rolling the ball into the back of the net for his first goal in Chelsea colours.
However, their lead didn't last long as Sunderland found themselves level on 21 minutes. The Blues failed to clear Nordi Mukiele's long throw-in, which resulted in Wilson Isidor poking the ball home from close range.
Chelsea dominated in the second half but struggled to break down a stubborn Black Cats side. They were eventually punished for failing to make their dominance count when Sunderland scored on the counterattack in added time.
Brian Brobbey pushed forward into the Chelsea half as he held the ball up excellently before setting up Chemsdine Talbi, who came rushing forward and curled a shot into the bottom right corner to send the away fans into raptures.
Story of the Match
Having heavily rotated on Wednesday night, Enzo Maresca made eight changes from the Ajax victory as Alejandro Garnacho and Pedro Neto started out wide with Joao Pedro playing in behind Marc Guiu, who retained his place.
Meanwhile, from Sunderland's 2-0 win over Wolves, defender Lutsharel Geertruida came in for the injured Omar Alderete, whilst Chris Rigg made way for Reinildo Mandava, who returned having served his three-match suspension.
The visitors had an early chance with just over a minute gone. A quick free-kick routine resulted in former Chelsea winger Bertrand Traore crossing towards Dan Ballard, whose header was straight at Robert Sanchez.
However, with just four minutes on the clock, Chelsea broke the deadlock. Neto forayed forward into the Sunderland half before playing through Garnacho down the left flank, who slotted home through the legs of Robin Roefs.
But Reggie Le Bris's side continued to cause problems for the Blues' defence. Enzo Le Fee came close from a free-kick as he curled the ball inches over the bar.
Though Chelsea were very much in the ascendancy as Reece James' corner resulted in Marc Cucurella seeing his shot blocked before the rebound fell to Caicedo, whose volley deflected over. From the resulting corner, a close-range strike from Garnacho hit the side netting.
However, midway through the first half, Sunderland found themselves level. A long throw-in from Nordi Mukiele was headed into the path of Traore, whose shot was poked home by Wilson Isidor for his fourth goal of the campaign.
The Frenchman almost got his second of the afternoon after latching onto Granit Xhaka's through ball, but hit the side netting. Meanwhile, the Blues threatened when Caicedo dispossessed Geertruida before sliding through Pedro, whose pass into the middle was blocked.
The home side looked to restore their advantage when a James corner fell to Garnacho at the backpost, but the Argentine's effort was kept out by Roefs. Traore then came close for the Black Cats, but his left-footed shot was comfortable for Sanchez.
In the closing stages of the first half, Trevoh Chalobah tried his luck from distance, but Roefs was alert to the danger, as the sides went in at the break all square.
Both sides continued to showcase their attacking intent after the restar,t though neither goalkeeper was called into action. Garnacho then cut in on his right but could only curl the ball off-target, as the winger was swiftly replaced by Estevao.
The Brazilian almost made an instant impact when Cucurella's cross found the youngster at the far post, who found space for a shot which deflected wide.
Chelsea continued to knock at the Sunderland door as Caicedo picked out Fernandez in the middle, whose first-time strike was easy for Roefs. The Argentine tested the Dutch goalkeeper again just minutes later, but his shot again proved easy.
Meanwhile, the visitors had a rare sighting of goal in the second half when Le Fee played through Xhaka, who cut in before seeing his attempt blocked by Josh Acheampong.
However, deep into added time, Sunderland scored what proved to be the winning goal. The ball was played over the top into the path of Brian Brobbey, who held the ball up before picking out Chemsdine Talbi, who curled the ball into the bottom right corner.
Player of the Match - Daniel Ballard
It was very much an excllent team performance from Sunderland rather than individual displays.
The away side were excellent defensively with Daniel Ballard putting a solid shift at the heart of the backline to keep out the Chelsea attack.