After snapping up Kaka, Real are in line to capture Cristiano Ronaldo from Manchester United for a staggering £80million.

United had no choice but to accept the astronomical offer from Spain for their star man, but Metzelder has reservations over the lofty figure.

"I don't know much about this evolution and I'm worried about it," the Germany center-half told The Sun.

"Spending this amount on someone that can get injured or be in bad form isn't correct to me, especially during this period of financial uncertainty."

Real have paid £62million for the services of Kaka, and they are reportedly in chase of David Villa and Franck Ribery.

The Spanish titans' new chairman Florentino Perez is targeting a number of high-profile signings this summer, as part of his 'project'.