The talented left-back arrived in Manchester this month after a deal was agreed with Primera Division side Cerro Porteno earlier this year in a move said be worth around £3.3M. United players reported to Carrington for training last week as manager Ruben Amorim puts his first-team players and youth academy talent through their paces after spending the summer recovering.
Now, Leon has signed a long-term contract at Old Trafford and has been handed the No30 shirt ahead of the new season. He has already started training with the first team who no doubt welcome the defender with open arms after their struggles at the back in the past few seasons.
United have no plans of sending the 18-year-old out on loan as Amorim hopes to introduce him into the first team in a bid to rework the defence that leaked 54 goals in the Premier League last season, more than Everton, Crystal Palace and the same as Fulham.
Leon previously wore no.37 at his previous club and no.4 for Paraguay's Under-20 national team and will now be preparing for tomorrow’s preseason clash against Leeds United who have now returned to the Premier League and will be the first big test for the Red Devils.