Champions Chelsea suffered a nightmare start to their Premier League title defence, having two men sent off as a Burnley claimed a superb win at Stamford Bridge.
Chelsea created numerous chances throughout, and it looked as if Mauricio Pochettino's men would pay for their wasteful finishing for a second consecutive match.
However, the home side ended the game with 10 men as defender Jan Vertonghen was sent off for catching Dortmund substitute Mario Gotze with a swinging arm.
Luis Enrique's men comfortably notched another win to their unbeaten run as they breezed to victory against out-of-form Eibar with two goals either side of half-time Barcelona extended their unbeaten run in all competitions to 36 matches after
They were reduced to 10 men when Reece James was shown a second yellow card for a foul on Gordon, before the former Everton man completed the scoring late on.
Barcelona were also reduced to 10 men in the last 15 minutes as substitute Jeremy Mathieu was shown a second yellow card for a foul on Raheem Sterling, but by then the damage had been done.
But in an instant Leicester were given a lifeline out of nowhere as Lucas Leiva -- deputising at centre-back for the injured Dejan Lovren -- gifted possession to Jamie Vardy inside the penalty area, who pounced on the opportunity to draw one
It was 2-0 before the half-hour mark as Swansea brilliantly carved through City and Nathan Dyer teed up Celina, who found the top-right corner with a curling effort from just inside the box.