The champions are not alone.
A huge summer splurge on transfer fees is likely after Premier League spending fell last year, in part due to a short window for clubs to complete their business between the end of the World Cup and a new transfer deadline, which fell before the season began.
The Premier League's transfer deadline will again come before most of the rest of Europe, on August 8, meaning clubs cannot afford to waste time.
The window for domestic deals opens on Thursday. International transfers can be completed from June 11.
AFP Sports looks at where each of the top six are set to strengthen.
The champions may have claimed a remarkable 198 points over two title-winning campaigns, but Pep Guardiola promised they will come back stronger next season and are likely to invest heavily for a variety of reasons.
A potential transfer ban due to a FIFA investigation over the recruitment of foreign minors and third-party ownership means this may be City's last chance to sign players for at least 18 months.
City could also face a season's ban from the Champions League by UEFA over financial fair play irregularities. If imposed, the sanction would likely be enforced for the 2020/21 campaign, giving City another chance next season to win the competition for the first time.
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Atletico Madrid's Rodri, who has a 70-million-euro ($78-million) buyout clause, has reportedly been targeted as the long-term replacement for 34-year-old Fernandinho in the holding midfield role.
A centre-back is also thought to be a priority, with City among clubs chasing Ajax wonderkid Matthijs de Ligt. Nicolas Otamendi and, perhaps, captain Vincent Kompany could depart.
Liverpool were the biggest Premier League spenders by a distance last summer and their £170-million ($219-million) investment was richly rewarded with the third-highest Premier League points tally ever and a return to the Champions League final.
No such splurge is expected at Anfield this summer as Klopp fine-tunes to dislodge City.
Alberto Moreno and Daniel Sturridge are set to leave on free transfers and cover is needed for Andy Robertson at left-back and up front as a back-up for Roberto Firmino.
Tottenham manager Mauricio Pochettino has worked wonders to get his side to the Champions League final and back into the competition next season despite not signing a single player since January 2018.
The Argentine, though, has been putting pressure on the famously frugal Tottenham board to back him this summer now the club have moved into their new 62,000-capacity home, which cost more than £1 billion and has slowed Spurs' spending in recent seasons.
Fulham's Ryan Sessegnon is a target as competition for Danny Rose at left-back, while the club needs a more potent back-up to Harry Kane than Fernando Llorente.
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The club has also been linked with a number of midfielders, including Barcelona's Andre Gomes, Youri Tielemans, who shone on loan at Leicester from Monaco, and Aston Villa captain Jack Grealish.
But they could be replacements for Christian Eriksen who is out of contract in 2020 like another key player Toby Alderweireld.
Chelsea may not be able to do any business at all as they are currently banned from signing players for the next two windows by FIFA.
The club plan to appeal to the Court of Arbitration for Sport and hope to have the ban suspended until the judgement.
Eden Hazard finally looks set to land his dream move to Real Madrid, leaving the Blues without their best player in recent seasons.
Christian Pulisic was signed in January to fill that void and will arrive from Borussia Dortmund, but Chelsea may be forced to rely on talented youngsters currently out on loan.
Arsenal's summer business will depend largely on whether they beat Chelsea in the Europa League final to seal a return to the Champions League.
An ageing defence that conceded 51 goals in the Premier League cost the Gunners a top-four finish and reinforcements are needed across the whole backline.
The departure of Aaron Ramsey also leaves a big hole in midfield.
United face by far the biggest rebuilding job after a disastrous season. They fail to qualify for the Champions League and finish as close to the relegation zone as to City in the league.
Ole Gunnar Solskjaer has promised big changes but much will depend on how many players on big contracts United can get rid of to free up funds.
Paul Pogba could be sold to Real Madrid, while Romelu Lukaku has attracted interest from Serie A.
A centre-back remains the priority, with Napoli's Kalidou Koulibaly the prime target, but the Senegalese is likely to cost a world-record fee for a defender.
Dortmund's Jadon Sancho has been linked with a return to England, but would cost more than £100 million.
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