Slowly but surely, Real Madrid president Florentino Perez is running the club's future into the ground. Two cornerstones have departed in successive seasons—Xabi Alonso to Bayern Munich and Iker Casillas to FC Porto-—leaving many to question who's next.

Below are three summer transfers Real Madrid must avoid to remain in within distance of Barcelona.

Sergio Ramos

According to the Mirror, Manchester United have verbally agreed to personal terms with Real Madrid for Sergio Ramos. Reports in Spain have the center-back set for showdown talks with his parent club.

It is imperative Real Madrid stray from any conversation leading to his departure.

Ramos was a key figure in Real Madrid's Champions League run in 2014, providing the stoppage-time equalizer in their 4-1 victory over Atletico Madrid. A world-class center-back in an era where few exist, finding a suitable replacement will be a virtual impossibility for Perez.

David De Gea

Any transfer involving Ramos to United will certainly feature David De Gea in return.

In addition to Keylor Navas—the 2013-14 La Liga Goalkeeper of the Year—Real acquired Kiko Casilla from Espanyol. Two serviceable men can handle the job between the posts. Paying any transfer fee for a player that can walk to the Spanish capital on a free in 12 months time is nothing more than excess spending.

Isco

Perhaps no player is more underappreciated in Madrid than Isco. Despite his talismanic talent and unprecedented versatility, the 23-year-old continues to be the subject of unnecessary transfer rumors.

According to AS (via Express), Manchester City and Chelsea are pursuing a £35 million bid.

Last season, it was injuries that raised Isco's value, seeing him fill multiple roles for James Rodriguez and Luka Modric. With rotation being a key part of Benitez's philosophy, selling off your first-choice substitute will be as catastrophic a decision as any.