France forward Antoine Griezmann has made a shock return to Atletico Madrid just two years after leaving to join Barcelona, on the final day of a hectic European transfer window.

Real Madrid also bagged a French international star as Eduardo Camavinga arrived from Rennes -- but their attempts to sign Kylian Mbappe from Paris Saint-Germain failed.

World Cup-winning 30-year-old Griezmann, who scored 133 goals in his first spell with Atletico, has rejoined on a one-year loan deal with an option to extend by another year and an obligation to buy, the club said.

"Welcome back, Griezmann!" Atletico wrote on its website.

Will Real Madrid target Kylian Mbappe be lining up alongside Lionel Messi at Paris Saint-Germain this season?
Will Real Madrid target Kylian Mbappe be lining up alongside Lionel Messi at Paris Saint-Germain this season? AFP / FRANCK FIFE

Barcelona have been struggling financially and had to allow six-time Ballon d'Or winner Lionel Messi to leave for PSG last month.

Midfield prodigy Camavinga, who is just 18, penned a six-year deal at Real, the club reportedly paying a fee of 31 million euros ($36.6m) plus nine million euros more in bonuses.

It is a considerable sum for the Angolan-born player, who was in the final year of his contract at Rennes.

Real had spent the last week trying to clinch a dizzying deal for 22-year-old forward Mbappe, making two bids, the last understood to be worth a total of 180 million euros.

Kylian Mbappe and Eduardo Camavinga together last year playing for France
Kylian Mbappe and Eduardo Camavinga together last year playing for France AFP / FRANCK FIFE

But PSG's Qatari owners do not need to sell and appear prepared to risk losing Mbappe for free at the end of the campaign in order to have the World Cup winner, Neymar and Messi together in attack for at least one season.

Real can come back in for Mbappe again in January, when they could sign him to a pre-contract agreement to move next summer without having to pay a transfer fee.

It has been an extraordinary summer transfer window in Europe, with Messi departing Barcelona for Paris and Cristiano Ronaldo on Tuesday finalising his sensational return to Manchester United from Juventus.

Apart from Messi, PSG have also signed Sergio Ramos from Real Madrid and one of the world's top goalkeepers, Gianluigi Donnarumma, from AC Milan.

Inter Milan sold Romelu Lukaku and replaced him with an ageing Edin Dzeko
Inter Milan sold Romelu Lukaku and replaced him with an ageing Edin Dzeko AFP / MIGUEL MEDINA

They also strengthened their midfield with Georginio Wijnaldum from Liverpool and signed flying Morocco right-back Achraf Hakimi, who shone for Inter Milan last season.

The latter cost some 60 million euros, with the rest all arriving as free agents.

On Tuesday, the club also announced the signing of teenage Portugal defender Nuno Mendes from Sporting Lisbon, on a season-long loan with an option to buy.

Ronaldo is the latest big-money signing in the Premier League, where the biggest deals have seen Manchester City buy Jack Grealish from Aston Villa for ?100 million ($138m) and Romelu Lukaku return to Chelsea from Inter for ?97.5 million.

Griezmann has rejoined Atletico on a one-year loan deal with an option to extend by another year
Griezmann has rejoined Atletico on a one-year loan deal with an option to extend by another year AFP / LLUIS GENE

In contrast, PSG apart, leading clubs on the continent have not been as willing to spend big money as they continue to suffer from the economic impact of the pandemic.

Before adding Camavinga, Real's only signing of note was David Alaba on a free from Bayern Munich.

Barcelona, mired in huge debts, could not keep Messi and spent deadline day selling off some of their talented youngsters.

Brazilian right-back Emerson Royal joined Tottenham Hotspur for 25 million euros after two seasons on loan with Real Betis, while teenager Ilaix Moriba headed to RB Leipzig for an initial 16 million euros.

Their only new permanent signings have been free agents, Eric Garcia and Sergio Aguero from Manchester City and Memphis Depay from Lyon.

They also announced a deadline-day deal to take Sevilla forward Luuk de Jong on loan.

In the Premier League, Chelsea secured the signing of Atletico midfielder Saul Niguez on a season-long loan, while Leeds signed Wales winger Dan James from Manchester United in a deal worth a reported ?25 million ($34.3 million).

Early strugglers Arsenal signed Japan defender Takehiro Tomiyasu from Bologna for a fee worth a reported ?19.8 million, and offloaded defender Hector Bellerin to Real Betis on a season-long loan.

In Italy, champions Inter replaced Lukaku and Hakimi with cheaper alternatives in Edin Dzeko and Netherlands right-back Denzel Dumfries.

They also signed Argentina's Joaquin Correa from Lazio on an initial one-year loan.

Juventus offloaded Ronaldo and signed two Italy internationals in striker Moise Kean and midfielder Manuel Locatelli.

Both arrived on loans that will become permanent after two years, a way for Juve to spread out the payments to Everton and Sassuolo respectively.

In Germany, Bayern Munich splashed a total of 67.5 million euros signing France defender Dayot Upamecano and Austria's Marcel Sabitzer from RB Leipzig.

Borussia Dortmund bought Dutch forward Donyell Malen from PSV Eindhoven and, crucially, have kept hold of Erling Haaland.