1-0 and up a man for Sean Dyche's visitors.
Spurred on by Cahill's dismissal, Burnley surged into a 3-0 half-time lead at Stamford Bridge courtesy of two goals from Sam Vokes either side of a spectacular Stephen Ward strike, and Chelsea could not salvage a draw despite a debut goal for Alvaro Morata and David Luiz's volley in the second half.
A few minutes after, Burnley piled more misery on Antonio Conte's wards, when S.Vokes found the net.
Conte will have some thinking to do, along with the board, as both Cahill and Fabregas will be missing for next week's match with Tottenham Hotspur.
Lady Killed in Triple Homicide, Police Arrested A Man in Long Island
The other woman who was visiting was injured but managed to escape and hide in a neighboring backyard until help could arrive. The accused, Bobby Vanderhall, was kicked out of his mother's house and was homeless at the time, police told NBC.
Stamford Bridge was stunned.
That was until Luiz sprinted onto Morata's pass and volleyed in to bring the nine men to within a goal of Burnley.
With Champions League football to contend with this season, the absence of proven goal scorer Diego Costa and injuries to others including star man Eden Hazard, their squad is looking dangerously thin.
Marcos Alonso's long-range drive was tipped over by Tom Heaton as Chelsea registered their first shot on target early in the second half, while Morata came on to replace the ineffective Michy Batshuayi in attack. He will need some help from his owner otherwise Chelsea really do risk having another "Mourinho season".
Arsenal beat Leicester City 4-3 in Premier League opener
Less than three minutes later, Olivier Giroud scored the victor for Arsenal , sparking celebrations at the Emirates Stadium. Leicester have since levelled the scores to 1-1 with Shinji Okazaki scoring just 160 seconds after Arsenal took the lead.
As well as worsening Chelsea's predicament, the Spaniard's dismissal marked the first occasion ever on which two players from the same team had been sent off on a Premier League opening day.
Conte cut an unhappy figure on the sideline, as he has done during most of pre-season and at Wembley last weekend. Still, the game had barely got out of second gear when Cahill received a straight red in the 14th minute for a high challenge on Steven Defour.
Cahill was made club captain following the departure of long-serving skipper John Terry at the end of last season. The biggest threat for Burnley is that a bigger club comes in and poaches him. They still had the quality to peg Burnley back, particularly as the visitors exhausted as the second half wore on, but lacked subtlety in their approach.
Chelsea had their first real chance at goal 11 minutes in when Cesar Azpilicueta's low cross was deflected and almost sat up for Willian to fire home in the centre of the goal.
Mourinho impressed by Lukaku & Matic despite mistakes in Real Madrid loss
Matic was frustrated with the result but has called on United to turn their full focus to Sunday's league opener against West Ham.
Despite the dire performance, the majority of the 41, 616 fans still cheered head coach Antonio Conte's name from the stands.