1157 GMT March 28, 2020
Mourinho took exception to the celebrations of one of Sarri's backroom staff, Marco Ianni, who ran in front of the Portuguese on the touchline, as he seemed set for a sweet victory over his old club after Anthony Martial scored twice to cancel out Antonio Rudiger's opener, AFP reported.
Players and coaches from both benches had to separate in a melee after Barkley's late strike.
Mourinho also then gestured with three fingers towards the Chelsea fans in reference to the three Premier League titles he won for the club in two spells in charge.
A draw is more than Mourinho got on his three previous returns to Stamford Bridge as United boss. But his frustration at blowing what could have been a huge win was obvious as the visitor remains seven points adrift of Chelsea.
Amid reports he was set to face the axe, Mourinho had been handed a lifeline by a stirring fightback from 2-0 down to beat Newcastle 3-2 before the international break a fortnight ago.
Martial was rewarded for coming off the bench to score in that game as rather than opt for his cautious nature, Mourinho named an adventurous lineup also featuring Juan Mata, Marcus Rashford and Romelu Lukaku.
And his gamble looked set to pay off despite falling behind to a Chelsea side now unbeaten in its first 12 games under Sarri.
Lukaku had the first significant chance of the game when he headed Luke Shaw's fine cross high and wide.
At the other end, United attempted to stop the outstanding player of the Premier League season so far with some rough treatment as Nemanja Matic and Ashley Young were shown early yellow cards for chopping down Eden Hazard.
However, when Shaw cut out a dangerous low cross from the Belgian on 21 minutes, the visitor was undone by a lack of concentration from Paul Pogba.
Rudiger easily peeled away from the Frenchman to plant a powerful header past the helpless David de Gea.
That was the fourth time United has conceded from a corner in the league this season, having also done so in defeats to Brighton, Tottenham and West Ham.
It was not so costly this time as Chelsea paid for a lack of killer instinct despite dominating possession for the rest of the first-half.
Marcos Alonso miscontrolled when Rudiger's through ball put him clean through on De Gea before Alvaro Morata wasted his only big chance of another disappointing afternoon when his shot on the turn was too weak to beat his Spanish international teammate in the United goal.
Martial had been largely anonymous before the break, but, in contrast to Morata, took his chances when they came in the second period.
Kepa Arrizabalaga parried Mata's initial effort, but with Alonso down injured in the Chelsea box, Martial had time to control Ashley Young's driven cross back into the area before firing home to equalize.
Martial again provided the final flourish with a brilliant curled effort into the far corner 17 minutes from time after fine work in the buildup by Mata and Rashford.
The Frenchman was greeted with a bear hug from Mourinho when he was replaced six minutes from time.
But United could not hold out for an extra six minutes stoppage time as Barkley pounced after De Gea had produced another miraculous save from Rudiger before carnage broke loose on the touchline.