LONDON, ENGLAND - AUGUST 12:  Michy Batshuayi of Chelsea is dejected after Burnley score their first goal during the Premier League match between Chelsea and Burnley at Stamford Bridge on August 12, 2017 in London, England.  (Photo by Dan Mullan/Getty Images)

5 Things We Learned From Burnley's Stunning Victory Against Chelsea at Stamford Bridge

It hasn't taken long for this Premier League season to provide some drama, and on Saturday reigning champions Chelsea were the victims of a stunning opening day result.

The Blues were beaten 3-2 against visiting Burnley, having gone 3-0 down in the first half following Gary Cahill's red card.

They came close to producing a comeback, even when Cesc Fabregas received his marching orders and they were left with nine players, but the Clarets held on to an unexpected, but hugely impressive victory.

Here are five things we learned from the game...

5. All Is Not Well at Chelsea

There was an atmosphere of tension at Stamford Bridge even before kick-off, not helped by the uncertainty surrounding the club's transfer activity this summer.

The players appeared to lack confidence, and it was an uncharacteristically ill-disciplined performance. Of course, they weren't helped by Gary Cahill's early red card, and Burnley were clinical and effective, particularly in the first half. But you get the feeling that last season's Chelsea would not have succumbed so easily.

It's early days, and there are key players still to return to Chelsea's squad, but fans will be concerned by the body language of players and staff in response to the surprise defeat.

4. Burnley Will Not Be Pushovers on the Road This Season

Last season, Burnley won just once away from Turf Moor, and it didn't come until late April.

They've already matched that with victory at Stamford Bridge, and perhaps they've proved a point, not just to those watching, but to themselves. There seemed to be a lack of belief about the Clarets on the road for much of last campaign, so that shouldn't be a problem after this performance.

Most assumed it would be a comfortable win for Chelsea, and were proven emphatically wrong. Circumstances may have aligned somewhat for Burnley on the day, but they should take no less confidence from a remarkable result against the Premier League champions.

3. Chelsea Really, Really Need Reinforcements

Antonio Conte has been stressing the need for Chelsea to bring in a number of new additions before the close of the transfer window, and his point was proved to an extent against Burnley.

Without the likes of Victor Moses, Tiémoué Bakayoko and Eden Hazard - plus Nemanja Matic following his sale to Manchester United, and the outbound Diego Costa - the Blues looked undeniably threadbare. The bench was made up largely of youngsters, and there were very few options to call on for Conte.

For a side that expect to challenge for the Premier League title again, and will hope to compete in the Champions League, Chelsea need far more squad depth.

2. Burnley Might Just Cope Without Michael Keane & Andre Gray

Some wrote off Burnley's chances of survival following the sales of two of last season's key players this summer.

Dependable centre-back Michael Keane departed for Everton, while striker Andre Gray left for Watford. Without them in the side, you'd expect an adverse effect, but against Chelsea, Burnley appeared to be even more of a cohesive unit.

Sam Vokes was excellent as a lone striker, scoring a brace and providing a dangerous focal points for his side's attacks. And at the back, James Tarkowski and Ben Mee were equally impressive.

1. Alvaro Morata Will Be Key for Chelsea

The Spanish forward, signed from Real Madrid for £60m this summer, certainly made an impact following his second half introduction against Burnley.

Morata began his side's revival with a well guided header to open his account and make the score 3-1. His movement caused the Burnley defence significant difficulty, and there was a notable improvement after he replaced the fairly subdued Michy Batshuayi.

With Diego Costa set to leave Chelsea, Morata's performances are likely to define the Blues' season.