America coach Miguel Herrera isn't surprised Chelsea are eyeing his young defender Diego Reyes.

The 20 year-old is already a Mexico international and being tracked by Chelsea.

"He will be very difficult to hold onto, there are many offers from Europe and he has confirmed his desire to leave to continue improving. Our idea is to have him here until June 2013, but anything can happen," said Herrera.

"This will depend on the number of bids and their size."