PSG aren't taking losing their Ligue 1 crown lightly, are they?
We're not two months on from the day Lille ended their long-standing dominance of French football, but the core of Les Parisiens' squad is nearly unrecognisable.
In Sergio Ramos, Georginio Wijnaldum and Achraf Hakimi, they have added quality and title-winning pedigree all over the pitch. And they've done it for roughly the cost of your monthly food shop - Hakimi is the only new signing they have spent a penny on so far.
It's difficult to quantify just how ridiculously good a signing he is. He's up there with Kylian Mbappe and Erling Haaland as the very best of his generation. He was Milan's captain at 21 years old. He was the best keeper in Serie A last season, and the best player at Euro 2020.
They've signed him for free.
Donnarumma is already one of the standout keepers in world football, up there with Alisson, Ederson and Jan Oblak, and he's going to be at the top of his game for at least another 15 years. Assuming they keep hold of him, PSG have basically made sure they won't have to splash out on a goalkeeper until 2036, maybe even beyond that if he follows the Gianluigi Buffon trend of playing into his 40s.
Comparisons with Buffon, himself a former PSG keeper, are inevitable, but Donnarumma stands up favourably to the best keeper of all time.
When Buffon was 22, he had only just established himself as Parma's first-choice keeper. He had fewer than ten international caps under his belt, but even that was pretty formidable for a keeper that age.
Donnarumma has played more than 250 times for Milan, captained them 24 times, and won the Euros as Italy's starting keeper.
Again: free transfer.
Goalkeepers tend not to peak until their early 30s, meaning Donnarumma has another decade before he produces his best football. But he is already playing at a level the vast majority of keepers will never reach.
His record from penalties, for one, is freakish. The average save percentage, for a mortal keeper, is 15-20%. After his three saves from the spot at the Euros, Donnarumma's sits at 34%.
Of all the penalties he has faced, including the fateful Bukayo Saka miss that won Italy the European Championships, less than half have resulted in goals.
Far from just a penalty specialist, however, Donnarumma stands out like this in virtually every metric. His almighty presence and command between the sticks led to 88 clean sheets for Milan, conceding goals at a rate of just over a goal per game.
Considering he was playing behind a pretty average defence for the most part - never finishing higher than fifth until his final season at San Siro - those numbers cast a very favourable reflection.
Almost every signing nowadays carries an element of risk. Even the free transfers of Wijnaldum and Ramos, each the wrong side of 30 and commanding formidable salaries, could prove to be missteps if not managed carefully by Mauricio Pochettino.
Donnarumma, however, takes care of himself. He's in his early 20s, he's already one of the best in the world in his position, he's a huge personality who inspires fear and respect from teammates and adversaries alike. There are, six weeks left in the window, but you can already say with confidence that this is the best bit of transfer business any club will do this summer.
And they've done it for free.