Here, the PA news agency compares the in-demand stars' records over the last three seasons.

Lionel Messi

Goals: 120 (since July 1, 2018)

Barca announced on Thursday that Messi "will not continue" with his only professional club, blaming LaLiga's financial regulations for their inability to conclude a new contract despite an agreement being in place.

While his last two seasons have not been at quite the astronomical standard of much of his previous career, he has still passed 30 goals in all competitions and is only two years removed from scoring 51 in 2018-19. He has won the Pichichi trophy as LaLiga's top scorer for five consecutive years and is coming off an overdue major tournament win with Argentina at the Copa America this summer.

Kylian Mbappe

Goals: 111

The man Messi would either partner or replace in Paris is also his most obvious heir as the most feared forward in the game and has scored 111 goals in the last three seasons.

Just 22 and already with a World Cup, four Ligue 1 titles and a Champions League final under his belt, he has already passed Messi's record for the most Champions League goals before turning 23 and has been Ligue 1's leading scorer in all of those last three campaigns – jointly with Monaco's Wissam Ben Yedder in the case of 2019-20.

Cristiano Ronaldo

Goals: 101

In any discussion centred on Messi, Ronaldo is never too far away. Between them, the pair won the Ballon d'Or every year from 2008 to 2017, with Messi also honoured in 2019 to give him six wins to Ronaldo's five, while they are far and away the all-time leading scorers in LaLiga and the Champions League with Ronaldo ahead in the latter competition.

Ronaldo left Real for Juve in the summer of 2018 and has raced to a century of goals for the Old Lady, with 37 and 36 in the last two seasons followed by a European Championship Golden Boot aged 36.

Erling Haaland

Goals: 97

At the other end of the age scale, it seems a matter of when rather than if the prodigious Haaland leaves Borussia Dortmund. Still only 21, the Norway international has been unstoppable for first Salzburg and then Dortmund since leaving Molde.

He was still playing for the Norwegian club in 2018, with the country's league taking place over the summer months, but taking only his goals since July 1 that year he has struck 97 times in 106 appearances across the three clubs as well as seven in 12 senior international caps.

Harry Kane

Goals: 81

After his run to the delayed Euro 2020 final with England, Kane has been absent from training with Tottenham this week but released a statement on Friday saying he has "never refused to train" and will report back "as planned" on Saturday.

He led the Premier League in both goals and assists last season, the only man to do so outright other than Andy Cole in 1993-94, and has 81 goals in all competitions over the last three seasons. With 166 Premier League goals in his career, he is chasing Alan Shearer's record of 260 in the competition.

Romelu Lukaku

Goals: 79

After a quiet final season with Manchester United in 2018-19, Lukaku has been a man reborn since his move to Serie A and helped Inter end Juve's long reign as champions last season.

The Belgian failed to establish himself in his previous spell at Chelsea but with 79 goals over the last three seasons, and 64 in the last two, it is easy to see why they are interested in a reunion.