The club has been included in a delayed pursue for Juventus midfielder Paul Pogba, however Mourinho declined to remark on the status of that arrangement.
"We are going to sign one more player without a doubt," Mourinho told BT Sport after Wayne Rooney's testimonial match on Wednesday night. "I would prefer not to talk about Paul (Pogba) in light of the fact that he is a Juventus player and I don't care for different directors to talk about my players. I don't talk about their players.
"However, actually we are going to sign one more player. The business sector closes, as you most likely are aware, August 31 so we have a lot of time to do that, yet I'd like to do it before the Premier League begins."
Joined's next match is the Community Shield against protecting League champions Leicester City on Sunday, before commencing their association battle away at Bournemouth the following weekend.
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