The Clarets made their numerical advantage count 10 minutes later as Vokes fired in his first of the afternoon from a Matt Lowton delivery.
Morata had a goal disallowed for offside but then Fabregas was sent off, perhaps harshly, for a tackle on Jack Cork with eight minutes remaining.
Burnley meanwhile had lost all their previous Premier League opening day fixtures before Saturday's triumph. Chelsea are also without Eden Hazard, Pedro and Tiemoue Bakayoko, who are all injured, and they sold Nemaja Matic this summer to Manchester United.
Chelsea to make improved £25m bid for Leicester midfielder Danny Drinkwater
Drinkwater featured in Europe's premier club competition last season after helping Leicester win the 2015/16 Premier League title. Drinkwater is said to be keen to move to the London club, despite not being guaranteed a place in the starting XI.
Coming into the new season as champions, Chelsea's prospective attacking problems had one silver lining: their defense would be undoubtedly solid. We kept a good shape early in the game, but the sending off makes a big difference.
Mounie, who joined the promoted side from France's Montpellier in July, scored his second goal 12 minutes from time in a counter-attack after being set up by substitute Collin Quaner.
"First half better, second half not as well, but they're a good side - their physicality, they're a strong side, they press high, fast, and it can put you off kilter". David Luiz really pushed the clash to the end with his 88th minute goal, but it wasn't enough to stop Sean Dyche's side recording a historic victory in the capital.
The Blues didn't come pouring out of the gates, either, though the hour mark saw a decent chance and shouts for a penalty as Burnley got extra chippy.
Jersey Shore Reunion Road Trip sneak peek announces premiere date
The Situation , meanwhile, admits that though "Pauly D was my boy in the house, it's been five years and we haven't spoken". The first official teaser for the brand new series Road Trip Reunion has finally been revealed.
New-look Everton had marginally the better of a disjointed opening spell with Sandro, another of their new signings, seeing an effort trundle just wide of the Stoke goal.
In the 3pm kick-offs, champions Chelsea were predicted to start their campaign with an easy win over Burnley at Stamford Bridge, only for Antonio Conte's men to find themselves 3-0 down at half time.
"A lot was made of our away form last season", Vokes said.
Jamie Carragher insists signing Virgil van Dijk won't solve Liverpool's defensive woes
If you want to win the Premier League , you've got to be conceding 30-35 goals. Watford should've been one-nil up before the corner, nothing changes.
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