The international transfer window was officially opened on June 11, which means the clubs can show their hands when it comes to signing up.
Real Madrid is looking for an expensive overhaul, Ajax has to deal with the disassembly of its talented offspring and how can Manchester City build on 197 points in two league campaigns?
In this sense Sports mail take a look at 10 questions that have yet to be answered this summer.
Many European clubs are facing a series of questions that crop up in the transfer window this summer
What must strengthen Manchester City?
Two seasons ago Manchester City finished with 100 points. Last season, they needed 97 points to win the league. Really remarkable numbers.
With Liverpool only one point behind last season, City boss Pep Guardiola is aware of the need to avoid complacency in trying to consolidate his position as England's best team.
David Silva is expected to retire late next season. Vincent Kompany has to be replaced in central defense, and Guardiola is still looking for a long-time successor to midfielder Fernandinho.
Joao Felix of Benfica, Bruno Fernandes of Sporting Lisbon, Rodri of Atletico Madrid and Harry Maguire of Leicester appear best in the Etihad Stadium.
The dominance of Manchester City domestically can not be taken for granted, as it is aimed at signatures
How can Liverpool build on their success?
Inland, they came so close. A single point was all that separated her from Moloch in Manchester City.
The victory in the Champions League was earned for a group that has lost the whole season only once in the Premier League. Now they have to step on the gas pedal instead of the brakes to stop waiting for a championship title.
Alisson and Virgil van Dijk, who won last year, already have one of the best backfives in the world. Trent Alexander-Arnold and Andy Robertson are among the best full-backs in Europe.
Ajax's Matthijs de Ligt remains interested in his ties to Van Dijk while strengthening the attacking options, with Lille's Nicolas Pepe an option, a focus on which Daniel Sturridge has already left and Divock Origi facing an uncertain future.
Liverpool must build on its success in the Champions League to get the championship title
What is Chelsea facing?
In a word: nothing.
The Blues face the task of not signing anyone this summer and have already lost Star Eden Hazard to Real Madrid with a £ 130m move, which could have a real impact on their fortunes.
With a number of lending stars and young players, Chelsea not only has little to offer but also has to boast products from academics like Tammy Abraham, Ruben Loftus-Cheek and Callum Hudson-Odoi during the high school season.
Uncertainty over boss Maurizio Sarri's position, which is closely linked to a return to Serie A at Juventus, keeps the coming summer on Stamford Bridge foggy.
The prospect of a two-window transfer ban ensures that Chelsea's transfer plans remain on hold
How does manager insecurity affect Barcelona?
The 4-0 loss to Liverpool in the Champions League semi-final is still a heavy blow for Ernesto Valverde.
Honestly, since assuming office, he has had two: The elimination of Roma in the Champions League in the penultimate season and what has turned out in Anfield last month.
The club is actively trying to put together a team that can secure them the desired Champions League title, which escaped them since 2015. Ajax star Frenkie de Jong comes for 65 million pounds.
De Ligt is another one they want to sign, while Antoine Griezmann's talk declines. Clarity about the manager seems to be the key to positioning all the other elements. Exclude a descent to Valverde and the rest should take care of themselves.
The uncertainty surrounding the future of Chef Ernesto Valverde is holding up the summer in Barcelona
Will Real Madrid continue to raise money?
When Zinedine Zidane returned to regain control of Real Madrid, it was clear he wanted money in the summer.
A sad end to the campaign led him to improve the mood with a £ 62m move for striker Luka Jovic, followed by the arrival of Hazard worth £ 130m. However, the club's big plans for overhaul show no sign of slowing down.
The Manchester United midfielder, Paul Pogba, is high on the list of priorities, and Christian Eriksen is also of interest.
The problem for Madrid is that they have to stick to financial fair play, which means they have to sell players to make up for the books. Gareth Bale, Isco, James Rodriguez and Mateo Kovacic all emerge from Zidane's plans, but the hard part is finding candidates for players who have long-term contracts with the club.
Madrid's summer depends on a few significant earners being transferred.
Zinedine Zidane is determined to close the gap with the rivals by reworking the Real Madrid squad
Trouble in paradise for Atletico?
It has already been announced that Griezmann will not appear in red and white in the coming season.
He says he already knows his next destination, but right now football fans are waiting to see where that turns out.
Diego Godin, a longtime defender of Atleti, is out of action and midfielder Rodri is a top target for Guardiola in the City.
Atletico and boss Diego Simeone are faced with the problem that they need to remain competitive while holding together a squad who wants to play for the club.
With much talk about Manchester United being scored against goalkeeper Jan Oblak and losing the spine of Oblak, Godin, Rodri and Griezmann, the team could devastate like no other summer.
Atletico Madrid may face a major reconstruction when stars like goalkeeper Jan Oblak leave the club
Is Ajax facing a squad rupture?
The Dutch giants were one of the stories of the 2018/19 season, as they resisted all expectations to reach the semi-finals of the Champions League.
The team of Erik ten Hag was driven by a talented young teammate and was only a matter of seconds before Tottenham's Lucas Moura broke his heart on home soil.
Talented midfielder De Jong is already a fixture, while interest in De Ligt, Donny van de Beek, Andre Onana, Hakim Ziyech, David Neres and Nicolas Tagliafico is huge.
For many, the price may never be so high again and the club could expect a price erosion of hundreds of millions. Given their success, there is the feeling of inevitability that this group will go their separate ways.
Matthijs de Ligt leads a number of Ajax stars who are attracting great attention this summer
Will Juventus build a team to challenge in Europe?
Cristiano Ronaldo was brought in to win Juventus, the Champions League. Fact.
They had already won seven consecutive titles in Serie A before the mercury Portuguese arrived in Turin. There were three direct trophies in Europe's biggest competition with Real Madrid before he arrived. There was a lot of hope that he could bring her to the first trophy since 1996.
He got them out of prison with a hat-trick against Atletico Madrid, but could do little against Ajax. Now Juventus has to go again and give Ronaldo the right side cast.
Paulo Dybala, under former boss Massimiliano Allegri, seemed ready to go this summer and that could still be the case. They need to brush up an aging defense, while talk of a return for Pogba continues to dominate the covers in Italy.
Aaron Ramsey is a clever business, but Ronaldo, who was asked after the Nations Cup final if he wants to exchange Amsterdam for Turin, needs more time to end the European Cup drought.
Cristiano Ronaldo was brought to Juventus to win the Champions League, but he needs help
But what about Conte … does Inter have the money?
Suddenly Juventus looks over his shoulder.
Her former boss Antonio Conte has returned to Serie A in a competing team, and Inter seems ready to make a splash on the market.
Their list of goals is a sign of high ambition: Romelu Lukaku, Eriksen, Bale, Fernandes and others.
Crowds are expected to come through the door at San Siro this summer as Conte wants to make Inter a top-four winner in the championship.
Inter Milan wants to challenge Juventus for the title in Serie A under Antonio Conte (left)
Is PSG faced with the choice between Mbappe and Neymar?
This one will probably run and run all summer.
Do Paris Saint-Germain have to choose between Kylian Mbappe and Neymar – or can they both stick to one side?
Both are able to be the star of the show, but two do not fit in, and the club knows they need to strengthen a number of other areas and may concede that they can not record them anymore.
On Tuesday it was reported in Spain that a divorce between Neymar and PSG was pending and the return to Spain would not materialize.
The focus on their strikers will be on France in the coming months.
The relationship between Kylian Mbappe (left) and Neymar (right) remains controversial