Villarreal director Jose Manuel Llaneza confirmed an approach from United for the services of the 30-year-old Spain international.

"Manchester rang us at the end of last week and asked us if we were prepared to sit down and negotiate," Llaneza was quoted as saying by El Mundo Deportivo on Tuesday.

"If the offer is good for everyone, the club would allow Marcos to leave," he added.

Spanish media reports claimed that Villarreal officials have set a 6 million Euro (4 million pounds) price tag on the combative player.

Villarreal coach Manuel Pellegrini was not happy with the prospect of letting go of the Brazilian-born midfielder but empathized with the opportunity playing for Manchester United represented.

"I understand that this is a great opportunity for him but, for us, it is going to be a great footballing loss if he does end up going," Pellegrini was quoted as saying by BBC Sports.

"If he leaves, I'll be happy for him but I will be sad for the team. He is a player who has proved his class and I have always found it very strange that nobody came in for him sooner as he is a great player."

Senna played a pivotal role in Villarreal's run to the semi-finals of the Champions League last season and was a member of Spain's World Cup squad earlier this summer.