During the 2017 summer transfer window, the future of the young Frenchman was one of the biggest 'soap operas' with several of the biggest clubs in Europe interested in his signature.
His former club Monaco were delighted as giants PSG and Real battled it out whilst the player's transfer value sky-rocketed. It would be the Ligue 1 champions who would go on to win the race to secure the forward's arrival at the Parc des Princes.
With the transfer finalised for a reported €145m plus €35m in add-ons, Mbappe will become the second-most-expensive player in football's history, when he permanently moves to the Parisian club this summer.
Now, former player Le Guen believes that Madrid missed a great opportunity to sign the French attacker, arguing that he would have been the perfect player to give continuity to 'Los Blancos'.
Le Guen said: "I think Real Madrid missed a great chance when they failed to convince Mbappe to sign for them, I think he would have been the ideal player to regenerate this squad, which did win two Champions League titles."
The Spanish club have had a disppointing first-half to the season, finding themselves 19 points behind rivals Barcelona in La Liga. A deficit that manager Zinedine Zidane will hope to reduce in the next few months.