How Sunderland's win at Chelsea sums up their brilliant start to life back in PL

Sunderland have made the best start by a promoted side in the Premier League for 17 years. So what are the secrets to their success?

The Black Cats stunned Chelsea 2-1 at Stamford Bridge on Saturday to briefly go second in the standings - an incredible storyline, given they were expected to be relegated straight back to the Championship.

Their supporters celebrated jubilantly in west London but there were plenty of signs in Sunderland's performance to suggest they can build on this fast start and steer well clear of the scrap at the bottom of the table. This was a win which summed up what has been so good about Regis Le Bris' team this season...

Defensive solidity provides platform for results

"Ballard! Ballard! Ballard!" That chant from the away section reverberated around Stamford Bridge as Sunderland repelled repeated Chelsea attacks, with their big No 5 making a game-high seven clearances.

But while Dan Ballard may have epitomised the commitment of his team to put their bodies on the line - and there were important blocks from Lutsharel Geertruida and Bertrand Traore - it was the Sunderland defensive system which frustrated Chelsea.

With Omar Alderete out, head coach Le Bris brought in Geertruida for his first start and employed the versatile Dutchman as a third centre-back out of possession. Nordi Mukiele shifted right to cover Trai Hume's moves into midfield when Sunderland won the ball back.

It was a complex game plan which required focus and problem-solving. Mukiele was seen in conversation with Le Bris and captain Granit Xhaka during the first half as they figured out how to plug gaps Alejandro Garnacho was moving into. But they worked it out.

The set-up was an adaptation of what they have been doing this season but showed their tactical flexibility and ability to frustrate when sitting in. Chelsea had 69 per cent possession but carved out just 0.97 worth of Expected Goals. "We didn't create a lot," conceded Blues boss Enzo Maresca afterwards.

He is not the first opposition manager to feel that way, with only Arsenal conceding fewer goals than Sunderland this season. That mean defence - brilliantly supported by goalkeeper Robin Roefs - is giving Sunderland's attackers the opportunity to earn them vital points.

Sunderland show resilience

Of course, that defence was breached early on, when Garnacho was given the chance to run in behind. But another trademark of Sunderland's strong start has been their resilience. They have won the joint-most points from losing positions among Premier League sides this season.

A flurry of chances followed for Chelsea to add to their opener but soon Sunderland gained a foothold and, by providing a threat of their own, evened up the contest.

This is a team which played for an hour with 10 men against Aston Villa and came back from a goal down to earn a point. They stay in the game and keep fighting. The late-turnaround win over Brentford back in August was another example of that.

A physical threat

The trend in the Premier League this season has been for teams to play in a more physical manner - and Sunderland are thriving in that environment. They have a towering line-up, with the spine of the team made up of players over six-foot tall. Only four teams have scored more headed goals.

That presence came to the fore for the equaliser at Chelsea, with Mukiele launching a long throw to cause chaos in the box before Wilson Isidor used his strength to hold off defenders to tap in.

There is energy in their performances, too. Central midfielders Xhaka and Noah Sadiki have covered more distance than any other players this season. Sunderland are physical powerhouses.

Xhaka leadership is getting most out of young team-mates

As well as that industry and his obvious quality on the ball, captain Xhaka leads his young team-mates with authority.

"He sets the standards every day," said Le Bris. "He's like a second coach on the pitch."

Sunderland's squad has the third-youngest average age in the Premier League but 33-year-old Xhaka is guiding them with his invaluable experience.

Savvy recruitment gives Le Bris options

Sunderland may have lost stars of their Championship promotion campaign, such as Jobe Bellingham and Tom Watson, but their heavy spending in the summer has given Le Bris a competitive squad.

It was a huge outlay - £183.4m spent, the most of any newly-promoted club over the past five seasons - but it is paying off right now.

Xhaka could be the signing of the season but Roefs, Sadiki, Alderete, Mukiele, Reinildo Mandava and the currently injured Habib Diarra are among the new arrivals to have impressed.

On Saturday, two combined for the winner, with Brian Brobbey shielding the ball before teeing up fellow sub Chemsdine Talbi to slot into the bottom corner. Isidor has also struck a couple off the bench this season, illustrating the options at Le Bris' disposal.

The impressive head coach is maximising Sunderland's strengths to defy the doubters.