Diego Costa struck twice but errors from Thibaut Courtois and Gary Cahill cost Chelsea victory at Swansea but there appeared to be an injury to John Terry before the final whistle.

Diego Costa had fired the Blues into a first half lead but the Belgian goalkeeper stupidly hurled himself at Gylfi Sigurdsson in the penalty area to concede a spot kick that the Iceland international dispatched with aplomb.

And, just moments later, Cahill was caught in possession by Leroy Fer who raced in to slot the ball past Courtois.

The England defender cried foul but Andre Marriner rejected his appeals and, even then, his poor first touch invited the Dutchman into challenge. With hindsight, Cahill would have played the ball straight to Courtois.

Costa, who was his usual warrior self, equalised with an overhead kick that went in off the face of Stephen Kingsley.

Here are five talking points to take from the 2-2 draw in south Wales.

Carding Costa

Diego Costa and Jordi Amat clash

Diego Costa will always polarise opinions amongst football fans. Chelsea fans love him for his goals and hard working. Opposition fans hate him for his antics which include over-elaborating an injury, theatrically going to the ground.

There were three bookings in the first half and all of them involved Costa in one way or another.

He was booked for a foul in the build up to Gylfi Sigurdsson's fine shot, while Leroy Fer and Federico Fernandez saw yellow for fouling the Spaniard.

There was also no love lost between Jordi Amat and Costa as the Swansea defender went into the book for a shove in the back early in the second half. Swans fans felt that the striker was milking the injury in order to get the defender booked and booed when the striker returned to the fray after treatment.

All that being said, the striker is normally deadly with the ball at his feet, powering home the opener inside the first 20 minutes although he should have had a second before the break when he missed from two yards out.

Criminal Courtois

Thibaut Courtois fouls Gylfi Sigurdsson and concedes the penalty

There was no need for Thibaut Courtois to leap into a challenge with Gylfi Sigurdsson just before the hour mark.

The Iceland international was in the corner of the penalty area and the ball was going away from goal, which is why the Belgian was only booked for the foul .

However, it was needless for the goalkeeper to launch into such a challenge what was unlikely to lead to a clear cut chance.

It was the catalyst for a five-minute collapse from the Blues that saw them go from leading comfortably to going behind.

Calamity Cahill

Gary Cahill of Chelsea in action

Gary Cahill then gifted Leroy Fer a goal when he tried to take a touch with the Dutchman bearing down on him.

Fer nipped in and put the ball past Courtois to give the home side the lead and put the England defender in the hotseat when David Luiz is up to speed.

Cahill felt he was fouled by Fer and, whether he was or wasn't, he shouldn't have been so lackadaisical with the ball in the first place.

It resulted in the Blues, from having been comfortably ahead three minutes earlier, chasing the game.

Fabulous Fabianski

Diego Costa slides to challenge goalkeeper Lukasz Fabianski

Chelsea would have won this game but for the fine goalkeeping of Lukasz Fabianski.

The Polish stopper made key saves to deny Willian, Costa among others and could do nothing about either goal conceded.

Some days, goalkeepers just have a good day and this was one of them. On another, the Blues would have won this comfortably.

England backlash

Midway through the first half, Chelsea fans launched into a chant of 'Eng-er-land' that was met with derision from the home supporters.

England may have beaten Wales in France but the Three Lions were the ones who flopped to Iceland while the Prinicipality reached the semi finals of the competition.

Swansea fans were quick to remind their Chelsea counterparts of these facts doing the Iceland handclap, singing Gylfi Sigurdsson's name and chanting Wales.

In this era, England fans can't claim any footballing superiority over Wales so if you're going to sing those songs, be prepared for a response you can't answer.