Senna has been a major transfer target for Manchester United coach Alex Ferguson who's looking to increase his midfield options, and Pellegrini said that the two clubs are on the verge of agreeing a deal for the 30-year-old.

"In the case of Marcos, nothing is 100 % finalized," Pellegrini told Marca on Thursday.

"I know that it'd a great opportunity for him, but for us it's going to be a great footballing loss if he ends up moving to Manchester."

Brazilian-born Senna joined Villareal in 2002 playing a pivotal role in helping the team to reach the UEFA Champions League semi final last season as well as featuring in Spain's World Cup campaign after being granted a Spanish passport.

"If he leaves I'll be sad for the team but happy for him."

"Senna is a player who has proved his class and I was always surprised nobody came in for him sooner as he's a great player," the Argentine coach considered.