Chelsea 'right to feel robbed by referee' at Swansea - Chris Sutton

Chelsea deserved to beat Swansea on Sunday and they feel they were robbed of victory by the referee. It is extremely difficult to argue with them.

Yes, Antonio Conte's side will rue the chances they missed in their 2-2 Premier League draw at the Liberty Stadium, but the bottom line is that Andre Marriner cost them two points.

Marriner's decision to allow Swansea's second goal was an absolute shocker. There is no other way of putting it, because Leroy Fer's foul on Chelsea defender Gary Cahill before he scored was as blatant as can be.

Swansea's first goal was poor from Chelsea's point of view because they were hit on the counter-attack from their own free-kick at the other end of the pitch.

But Chelsea were totally in control up until that point and, although they had made a mistake, I still felt they were well in the ascendancy.

As Cahill said afterwards, it was Swansea's second goal only three minutes later that killed them - and Marriner's mistake was inexcusable.

It is an assault by Fer - there is not one foul, there is two - and it is ridiculous that play was allowed to continue.

One of the positives that Chelsea can take from the day is that they fought back to rescue a point with Diego Costa's second goal of the game.

The Blues have now earned five points from goals in the last 10 minutes of games this season, more than any other top-flight team, but they should never have been in a situation where they were chasing the game.

Costa looks back to his best

Costa now has four goals from four Premier League appearances this season and I was really impressed by his movement, his confidence and his all-round play.

He was a focal point all game. He was showing for the ball, and held it up really well to buy time for his team to advance up the pitch.

The Spain striker wasted a big chance to put Chelsea 2-0 up before half-time when he missed from close range, but he was a real handful and looks like he is back to his best form.

His first goal against Swansea, a first-time shot from Oscar's pass that he caressed into the corner, was a superb finish and his second was acrobatic and exceptional.

We know he plays near the edge - he was booked for the third time this season - and oversteps the mark sometimes, but that is part of his game.

Swansea defenders Jordi Amat and Federico Fernandez were both booked by referee Andre Marriner for fouls on Costa

Swansea tried to rough him up at the start of the match but he does not mind that side of things.

He should have a hat-trick and he looked very sharp, which is a worrying sign for Premier League defenders.

Conte making a difference already

Chelsea had 14 shots in the first half and looked in total control against a Swansea side that were poor and did not look a threat.

It was astonishing that the Blues ended up dropping their first points of the season and they will feel like they actually lost the game because they had made such a good start.

Chelsea still have 10 points out of 12 and they can be pleased and positive with the way they have started the season, but it will be very frustrating for them to lose their 100% record like that.

I like the way Conte manages - he is all about graft and it already looks like he is getting a lot out of his players.

This is a Chelsea team that under-performed last season but N'Golo Kante was the only player to start against Swansea who has joined since, and you could not accuse them of not working hard enough in Wales.

Chelsea's three league wins this season have come against West Ham, Watford and Burnley. You could argue they should be beating those teams, but they did not manage it last season - they only took two points from the same games against the Hammers and the Hornets.

They are clearly going to do better than their 10th-place finish last time out, but the question is how much of an improvement will there be.

They will want to get back in the Champions League and they probably have title aspirations too. Manchester City look a different class to everyone else so far, but the rest of the top four looks wide open.

We will find out a lot more about Chelsea's prospects in their next two league games - at home to Liverpool on Friday (20:00 BST kick-off) and away to Arsenal the following weekend.

Those head-to-heads will be very important but I can see all the top teams taking points off each other when they meet.

The race for the top four threatens to be very close, so it is even more disappointing for Chelsea that they slipped up against a team like Swansea, because those are the games they definitely should be winning.

Chris Sutton was speaking to BBC Sport's Chris Bevan.