Xabi Alonso can take plenty of encouragement from deploying a back three for the first time at Chelsea – conclusively beating AC Milan 3-0.The display was a far cry from Chelsea’s leaky defensive performances in pre-season so far, as they kept their first clean sheet since Alonso took charge.Chelsea were dominant throughout, helped by having consistent personnel on the pitch – making only two changes before 80 minutes, whereas AC Milan made wholesale substitutions at half-time.But it was the defensive structure Alonso utilised so effectively at Bayer Leverkusen that enabled a comfortable performance. Summer signing Marco Palestra was deployed at left wing-back, with Pedro Neto on the opposite side. In possession, though, they may as well have been wingers.When Chelsea attacked, Neto ran beyond Palmer – who started on the right of Danny Welbeck – offering a penetrating threat to stretch play. Palestra acted the same way on the opposite side as his perpetual movement shone.Not only did the set-up allow Chelsea to threaten all over the pitch with significant offensive threats occupying both wide and narrow areas, but the front three demonstrated their fluidity.Joao Pedro, Cole Palmer and Danny Welbeck often rotated. At times, there were two up top with one behind. The main formation, though, was a 3-4-2-1.Welbeck led the line with Palmer and Pedro either side of him. But that was not a strict rule, as the attackers were given the freedom to roam.A link-up between Pedro and Neto earned Chelsea their second less than a minute after half-time. Neto found Pedro’s run with a dinked cross into the box from the right.Neto had very few defensive responsibilities as the right wing-back, allowing him to focus on being a nuisance.That right side could prove deadly during the season, with full-backs forced to deal with the menacing Palmer inside while also keeping tabs on the threat Neto poses out wide.Pedro, meanwhile, flourished in the system. Encouraged to float around, the technical Brazilian demonstrated his versatility as a number 10 who can also play out wide and up front. Joao Pedro has been on fire during pre-season, scoring five times, and Xabi Alonso’s back three seemed to bring out the best in himFour shots, two goals, a big chance missed and the most touches in the AC Milan box – Pedro, thanks to the set-up, was extremely active and took his pre-season tally to five goals.Josh Acheampong was also a beneficiary of the system, exuding confidence both on and off the ball. The centre-back recovered brilliantly to make a last-ditch challenge on Rafael Leao in the first half, strong in the tackle – putting his mistake behind him.With the likes of Reece James, Maxence Lacroix, Enzo Fernandez, Malo Gusto and Morgan Rogers to report for the remainder of pre-season next week, Alonso has every right to be excited about this Chelsea side.At 70 per cent strength, Chelsea looked cohesive and controlled, with four games now under their belt and an encouraging understanding of what is required in a back three.As even more quality is added to the group next week, the back three looks an appealing option to open their Premier League campaign against Fulham.MacPhee’s immediate impactNew set-piece coach Austin MacPhee has already started to earn his money.Chelsea paid a release clause just shy of £1million to get him out of his contract at Aston Villa and bring him to Stamford Bridge. Minuscule in the context of player spend, but significant for a member of the backroom staff.Yet he could prove to be Chelsea’s most important signing of the summer.Chelsea had an appalling record from set-pieces last season, with a negative goal difference from them – conceding 17 and scoring 14. It is no wonder Alonso was so keen to add one of the world’s best dead-ball coaches to his coaching staff.Having joined Chelsea just this week – flying to Asia to unite with his new side on their pre-season tour – MacPhee made a blazing impact, with Chelsea scoring twice from corners against AC Milan. Chelsea scored twice from set-pieces against AC Milan, with Moises Caicedo finding the back of the net from outside of the areaThe first was pretty basic. Moises Caicedo’s pinpoint cross found Pedro’s intelligent movement. Pedro, unmarked, glanced his header into the far corner. It was a goal you will see many times this season.The second, however, was certainly a move crafted on the training ground as MacPhee’s expertise emerged. Romeo Lavia floated a cross to the edge of the area where Caicedo was waiting. The midfielder coolly came onto the ball and ingeniously guided it into the bottom corner with the outside of his boot. He made a tough finish appear straightforward – it was anything but. A move executed with individual brilliance, but one crafted by Chelsea’s new master in the dugout. If this is just a glimpse of MacPhee’s capabilities, Chelsea certainly have plenty to look forward to.