This summer marks four years since Robert Lewandowski infamously completed a free transfer from Borussia Dortmund to Bayern Munich.

During that time, the Poland international has won the Bundesliga three times - soon to be four - one DFB-Pokal, two DFL-Supercups and the Bundesliga Golden Boot twice.

He's been phenomenal in Bavaria, but it would appear the time has come for Bayern to start searching for his replacement.

Lewandowski has been linked with a move away from the Allianz Arena for the best part of two years now and reports suggest it will finally happen this summer.

But who could he join?

Real Madrid and Paris Saint-Germain are both very interested as they look to replace Karim Benzema and Edinson Cavani respectively.

There's interest from the Premier League, too, with Manchester United, Manchester City, Arsenal and Chelsea all known admirers of the 29-year-old.

However, manager Jupp Heynckes hopes Lewandowski will stay at Bayern, which he described recently as the "summit" of European football.

"Lewandowski would be well advised to focus on Bayern," Heynckes said. "He is internationally one of the best players in his position.

"Bayern is something very special at European level. If I were a player, I would always decide for Bayern. Bayern is the summit."

Heynckes' attempts to keep Lewandowski appear to be in vain, though, with Mundo Deportivo reporting that the Polish striker has an 'agreement in principle' to join another club.

And that club, unsurprisingly, is Real Madrid.

Lewandowski's agent, Pini Zahavi, and Real president Florentinio Perez's right-hand man, Jose Angel Sanchez, met twice recently to confirm that Lewandowski wants a move.

The reason it's only an 'agreement in principle' at this stage is because Bayern haven't agreed to sell yet, though Lewandowski has already been offered a two-year contract.

Real previously wanted Tottenham's Harry Kane but targeted Lewandowski instead when Spurs were refusing to budge.