In June, Saudi Arabia's Public Investment Fund (PIF) took control of four teams in the Saudi Pro League. Those being the founding members - Al Ahli, Al Ittihad, Al Hilal and Al Nassr. Since then, player after player has joined the division.
Cristiano Ronaldo joining Al Nassr in January was the first significant arrival for the league and in the months since, a succession of big-money, big-name moves such as Karim Benzema and Riyad Mahrez have followed.
We track all the moves, club by club.
A whole host of clubs have been scrambling to make squad additions and keep pace with their rivals and away from the four PIF-owned clubs, others have seen ownership structures change with outside investment.
The result: signings have been racking up as the season starts. But who is headed where?
Last season's title winners Al Ittihad made waves in early June with the signing of Real Madrid's Karim Benzema on a free transfer. The marksman penned a two-year deal worth 400 million euros, which somehow makes the 100 million euro four-year deal for France teammate N'Golo Kante, who followed on a free from Chelsea, seem paltry in comparison.
Linking up with Benzema and Kante is Celtic's Jota, who scored 28 goals across two seasons in Glasgow before departing for £25 million this July. He joins the Jeddah-based outfit on a three-year contract.
Another marquee signing for ex-Tottenham and Wolves boss Nuno Espirito Santo came at the end of July, with Fabinho secured from Liverpool for £40m. The 29-year-old, who signed a three-year deal, made 219 appearances for the Reds.
Cristiano Ronaldo’s move last July was headline news worldwide and set the ball in motion for other high-profile arrivals.
After a second-place finish last term. Al Nassr didn’t hang around this summer, bringing in Marcelo Brozovic from Inter for 18 million euros, with the Croatia international opting for Riyadh despite interest from Barcelona.
Following Brozovic to the Saudi capital for 25 million euros was 28-year-old Ivorian midfielder Seko Fofana, who helped Lens finish second in Ligue 1 last season, and Manchester United defender Alex Telles, who won the Europa League on loan at Sevilla.
Sadio Mane became this year’s headline signing when his move from Bayern Munich – for £24 million – was announced in August. The Senegal international failed to find his best form in Germany, scoring just 12 goals and falling out of favour.
Bringing in Neymar for 90 million euros could go down as the coup of the window, with Brazil's record scorer committing two years to the club, but Al Hilal were busy long before that.
Wolves were paid a club-record fee of £47 million for captain Ruben Neves in late June, just a day before Kalidou Koulibaly joined from Chelsea for £17 million, a year after his move from Napoli for roughly double the price.
July saw Sergej Milinkovic-Savic swap the Italian capital for the Saudi one, ending eight years at Lazio for a transfer fee of 40 million euros.
Brazilian winger Malcom was prised from Zenit for 60 million euros after top-scoring in the Russian league last season with Fulham's Aleksandar Mitrovic making the move in mid-August for £46 million.
Al Hilal have also reinforced between the posts, with Morocco goalkeeper Yassine Bounou joining from Sevilla for 21 million euros.
Seventh last season, Al Ettifaq's most notable summer arrival saw Steven Gerrard take his place in the dugout, taking the managerial reins eight months after his sacking by Aston Villa.
His first move was to pay Liverpool £12m for his former teammate Jordan Henderson, with Moussa Dembele and Jack Hendry then arriving on the same day in late July.
Striker Dembele joined on a four-year deal after his Lyon contract expired, while Scotland international defender Hendry commanded a £6.5 million fee for his move from Club Brugge, after spending time on loan at Cremonese in Serie A last term.
Promoted back to the top flight last season at the first time of asking, Al Ahli made statements in signing goalkeeper Edouard Mendy - £16 million from Chelsea - and Roberto Firmino - from Liverpool, as a free agent.
But Al Ahli weren't done. Riyad Mahrez followed in a deal worth £30 million to Manchester City, as did Newcastle's Allan Saint-Maximin for an undisclosed fee.
Defender Franck Kessie joined the ranks in August from Barcelona for 12 million euros.
There have been off-the-field changes too, with Matthias Jaissle taking the vacant managerial spot after his dismissal from RB Salzburg.