Ahead of his debut season at
In a series of snaps on his Instagram, the former Chelsea coach is seen relaxing.
His rebuilding job at Manchester United began when Ivory Coast central defender Eric Bailly became his first signing, joining from Spanish side Villarreal.
The 22-year-old signed a four-year contract with an option for two more years, a club statement said.
The capture of Bailly marks the first of an expected flurry of signings by Mourinho as he seeks to restore the fortunes of the 20-times English champions who won the FA Cup last season but finished fifth in the Premier League.
United, who will play in the Europa league after missing out on Champions League place, are also favourites to sign Sweden striker Zlatan Ibrahimovic while Juventus midfielder Paul Pogba has also been linked with a move to Old Trafford.