The Guardian says the emergence of Ben Foster has given the veteran Dutchman cause for concern. Van der Sar is contracted to United until 2009 but the Dutchman, who plans to retire from international football after this summer's European Championship, is understood to be contemplating a return to the Netherlands this summer.

The popular belief at United is that Foster will establish himself as Sir Alex Ferguson's first-choice goalkeeper next season and it is doubtful whether Van der Sar will tolerate being a substitute.