Perez returned to the Real presidency last June, three years after having walked out on the nine-times European champions, saying he had learned lessons from his previous six-year tenure.
He pledged to build a "spectacular sporting project" to put the club back at the forefront of European and world football, spending close to a quarter of a billion euros to sign Cristiano Ronaldo, Kaka and Karim Benzema among others.
Pellegrini was lured from Villarreal to manage the new project, Real director general Jorge Valdano describing him as "the (Arsene) Wenger of Spain", and he was given a two-year contract.
"Big clubs are always required to win every Sunday and it's difficult to keep a project going if that's not happening," Chilean Pellegrini said at his presentation.
"But usually those that have a long-term project and know how to keep it going are those that get the best results."
The first hiccups came with the calamitous King's Cup exit to third-tier side Alcorcon in November, but Perez insisted his eye was fixed on future as the Madrid-based media called for the coach's head.
"Our dream is to build a spectacular team but it would not be a failure if we didn't win a title," Perez told Spanish television that month.
"We are at the start of a new project. We are giving it stability. We aren't going to get nervous because it hasn't all come together perfectly in the first year."
Defeat at arch rivals Barcelona in the "clasico" in December and again in April were tough shots to take but perhaps the most painful was Real's exit to Olympique Lyon in the Champions League last 16 in March.
There is a huge temptation to go for Inter Milan's Mourinho as coach for next season, with the Portuguese on the brink of an unprecedented treble for an Italian side if he can win the Champions League final on Saturday.
