Scot is desperate to bring new players in to Old Trafford for next season.
Manchester United head coach David Moyes flew to Portugal on Wednesday night to personally check out a series of potential summer transfer targets, according to reports in the Daily Mail.
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The Premier League champions are set to embark on a massive squad overhaul at Old Trafford come the end of the campaign, with a number of different areas of the team in need of freshening up.
And the players that the Scot are understood to have been running his eye over in the Portuguese capital, where champions FC Porto were taking on arch-rivals Benfica in the Portuguese Cup semi-final, were France international centre-back Eliaquim Mangala, Colombia international front man Jackson Martinez and left-back Guilherme Siqueira.
However, of that trio of possible summer targets, it is believed that it is Porto central defender Mangala who Moyes is most interested in luring to Old Trafford next season.