Sooner or later, something was going to rain on Milan’s parade. At first it seemed like it might be the actual rain, as the skies opened above Rome on Sunday, dumping four inches of water on the capital in three hours. As streets were submerged and public transport ground to a halt, it seemed inevitable that the Rossoneri’s game away to Lazio would need to be pushed back to a later date.

Instead, it was postponed for just one hour: officials trusting in both the weather forecast and the pitch drainage system at the Stadio Olimpico. From a logistical standpoint, it turned out to be the right decision. With hindsight, however, Milan might have wished for more time to prepare.

Here was the first true test of their extraordinary summer rebuild. Milan had begun the season in encouraging form, winning six consecutive games between Europa League qualifying and Serie A.

Paulo Dybala’s fine strike caps Juventus’s home victory over Chievo Read more

But you don’t splurge €200m on new signings just to make life easier against Crotone and Craiova. Returning to the Champions League is not so much an ambition as an economic imperative for Li Yonghong’s new ownership group, and Lazio will be direct rivals in the race for the top four.

It would be absurd to talk of must-win games so early in the campaign, but at the very least this felt like a must-prove-that-we-are-headed-in-the-right-direction game. In that, Milan failed. On a day when the city hosting them flooded, they contrived to go down in flames.

There was a brief period, at the start, when they played with conviction, laying claim to the ball and forcing their hosts onto the back foot. Even then, though, they rarely threatened. The 19-year-old striker Patrick Cutrone, after excelling against lesser opponents, was bullied by Stefan Radu and Stefan De Vrij. Fabio Borini was woeful on the left of attack. Even Suso, on the opposite flank, looked subdued.

Lazio, by contrast, were swift, direct and clinical. They took the lead in the 38th minute, Ciro Immobile blasting home from the penalty spot after being felled by Franck Kessié. They were 4-0 up by the 49th, the striker completing a hat-trick either side of the break before teeing up Luis Alberto for the fourth.

Immobile was brilliant, exploiting the spaces left by Milan and taking his chances with aplomb. He is the first Lazio player to score three against Milan since 1942.

Behind him, Lazio dominated the midfield even whilst allowing Milan to enjoy more than 60% of the possession. Lucas Leiva and Marco Parolo provided a steady shield in front of the defence, while Luis Alberto and Sergej Milinkovic-Savic gave the team length, slipping back into midfield to help combat the Milan press before racing forwards to support Immobile on each counter.

Most of all, Lazio were cohesive – a tight unit in which every player had a clear sense of their role. A testament, in short, to Simone Inzaghi, who is quietly establishing himself as one of the most promising tacticians on the peninsula. He confessed afterwards that he had been devastated when it appeared that the game might be called off, when he knew that his team had prepared it just right.

Facebook Twitter Pinterest Ciro Immobile takes the acclaim from Lazio supporters after his hat-trick. Photograph: Vincenzo Pinto/AFP/Getty Images

Milan were the opposite: a ragged mess of individuals, a truth which their own manager, Vincenzo Montella, acknowledged at the end. “We didn’t have the mental strength to react,” he observed. “Everyone wanted to fix things on their own.”

They would pull one goal back through Riccardo Montolivo: insufficient to disguise how poor they had been. Montella’s decision to leave several of this summer’s highest profile additions out of his starting XI – from André Silva to Hakan Calhanoglu and Nikola Kalinic – might raise eyebrows, though the latter two both entered as second-half substitutes without making any great impact on the game.

The absence of right-back Andrea Conti, who impressed last season at Atalanta and has continued to do so in Milan, was damaging, but cannot be an excuse on its own for such a defeat. It was the club’s most expensive signing, meanwhile, who put in the most disappointing performance of all.

Luring Leonardo Bonucci from Juventus was the greatest coup of a spectacular summer. Besides being one of the best defenders on the planet, this was a guy who could bring a dash of that elusive ‘winning mentality’ – a player who had won six consecutive Scudetti and been to two of the last three Champions League finals. He was immediately handed the Milan captaincy.

As with the rest of the side, early performances had been encouraging, but on Sunday he was all at sea. Bonucci lost track of Immobile at the back post on Lazio’s second goal, and seemed to get caught in no man’s land on the third as well. For the fourth he was nowhere to be seen, having been caught up the pitch attempting to support the attack.

Gazzetta dello Sport named him the worst player on the pitch, with a rating of four out of 10. That might have been taking things a bit far, but this was not a good day at the office. At times Bonucci was guilty of getting drawn out of position in a bid to cover for team-mates’ mistakes, but in other moments he was simply losing his one-on-one battles.

He has not forgotten to defend overnight, of course, and none should doubt that better days lie ahead. Having Alessio Romagnoli back to full fitness will be a boon – permitting Montella to move beyond his current 4-3-3 and experiment with a three-man defence similar to the one that Bonucci was part of most often in Turin.

These are still early days for a project with grand ambitions. If Rome was not built in a day, then Milan cannot be restored to the pinnacle of world football in a single summer, either. Nevertheless, a defeat this heavy cannot be shrugged off completely. Sharp improvement is required if this team hopes to weather further storms that lie ahead.

Talking points

• Just the five goals for Fiorentina as they blitzed Verona at the Bentegodi. That scoreline, it must be said, owed a lot to the hosts’ deficiencies but after defeats to Inter and Sampdoria this was a timely result for a young Viola team, featuring the 22-year-old Giovanni Simeone (son of Diego) and the 19-year-old Federico Chiesa (son of Enrica) in its front line. This might not be the strongest Fiorentina side we have seen in recent years, but with five other players under 26 in the starting lineup at the weekend, it is certainly a young one, and it will be interesting to watch it develop.

• And while you’re waiting for that to happen, maybe just stop for the next year to admire Jordan Veretout’s free-kick.

ACF Fiorentina BRA (@AcfFiorentinaBr) Você que não viu o Golaço de Jordan Veretout, Confere ai essa Pintura:#ForzaViola pic.twitter.com/ntLj74Edfp

• Another round of games, another round of VAR conversations. Claudio Gavillucci had initially awarded Inter a free-kick when João Mário was brought down by SPAL’s Francesco Vicari on the edge of the box, but replays showed pretty quickly that this should have been a penalty. So why did it take five minutes for the referee to reach the same conclusion? I’m still inclined to call these teething problems which should improve over time, but I can see why people get frustrated.

• The game was Inter-SPAL. And the sponsor on SPAL’s shirt?



Andrea Motta (@neoandrea) #InterSpal: it's funny to see this sponsor today on #Spal's shirt. #SerieA pic.twitter.com/8d0tMQD0sa

• Wins for Inter, Juventus and Napoli mean those three remain level at the top on maximum points. Sampdoria were denied the chance to keep pace after their game against Roma was postponed due to rain in Genoa.

• It was interesting to see how Massimiliano Allegri shuffled his deck before Juve’s Champions League game against Barcelona this week. Wojciech Szczesny made his debut in goal, while Blaise Matuidi and Douglas Costa both got their first starts for the club as well. In the end, though, things still got a lot more straightforward for the Bianconeri once Paulo Dybala had come on to replace the latter member of that trio.



• Rodrigo Palacio: better at American football tackling than the Milan native who made his (otherwise highly successful) NFL debut on Sunday night.



Results: Atalanta 2-1 Sassuolo, Benevento 0-1 Torino, Bologna 0-3 Napoli, Cagliari 1-0 Crotone, Inter 2-0 SPAL, Juventus 3-0 Chievo, Laizo 4-1 Milan, Udinese 1-0 Genoa, Verona 0-5 Fiorentina