Frank de Boer was aware of the need for defensive reinforcements and did have a tentative interest in Daley Blind and is delighted to be reunited with his fellow former Ajax man, adding: 'Timothy is a player who has great pace and incredible physical ability.
Crystal palace play Premier League new boys Huddersfield on Saturday and the game could come to early for Fosu-Mensah, although he would be eligible to play if De Boer considers him ready.
'I must now repay that back by putting in some good performances for the club.More news: North Korea risks 'destruction of its people', says defence secretary Mattis
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The 19-year-old has signed a one-year contract at Selhurst Park and will wear the No.24 shirt.
The Dutch youngster had been expected to provide cover for Antonio Valencia down the right this season but the decision to allow him to leave on loan could indicate United's transfer business is not done yet.
Widely seen as one of the club's standout prospects, previous year Fosu-Mensah signed a new deal that ties him until the summer of 2020. One potential stumbling block in the move however is whether the Ivory Coast global is given permission to enter the United Kingdom amid an ongoing legal issue. He spent the first two years with the Red Devils' academy, before making his first team debut against Arsenal in February 2016.