Lukaku became Manchester United’s second signing of the summer last week when he joined the Red Devils from Everton on a long-term contract.
Victor Lindelof signed for the Red Devils from Benfica last month as Mourinho moved quickly to bolster his attacking options at Old Trafford ahead of next season.
And the Portuguese coach has revealed how he spoke to both players after they linked up with his squad to inform them of how fortunate they are to have joined the Red Devils.
Mourinho told a news conference in LA on Friday: “I told Lukaku and Lindelof on the day we started that they are very lucky to belong to such a group, not because they don’t deserve it from a professional point of view because they did very well at Everton and Benfica.
“But because the group is a really special group and it is amazing for a player to change club and feel that the group is fantastic.
“I feel they will be here for a long time.”
Manchester United are preparing for a return to the Champions League next season after Mourinho led the Red Devils to Europa League glory last term.
The Red Devils also won the EFL Cup last season but finished in a disappointing sixth place in the Premier League table.
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