Jose Mourinho ruled out any attempt to bring Cristiano Ronaldo back to Old Trafford after Manchester United opened their US tour with a 5-2 rout of the LA Galaxy.
United manager Mourinho is keen to bolster his ranks further after already strengthening his squad with the additions of Victor Lindelof and Romelu Lukaku, who both made their debuts at the StubHub Center.
But the Portuguese manager dismissed the possibility of a move to bring Ronaldo back to Old Trafford from Real Madrid.
"We have never thought about it because he is too much of an important player for his club, of great economic power," he said.
"We have not been able to find for whatever reason anything that could have made us think that Ronaldo could leave.
"I'm not going to waste my time thinking about players who are mission impossible."
Mourinho gave a list of summer targets to executive vice-chairman Ed Woodward with the hope of making four top-quality additions.
United have so far brought in Lindelof and Lukaku, with the latter's arrival said to have ended their interest in Real Madrid striker Alvaro Morata.
"He belongs to Madrid," said former Real boss Mourinho. "Madrid have decided and we have not come to an agreement. It is simple. It is a shame.
"He is a player who made it to the first team with me. We have a special liking for him, he is someone special. I enjoyed watching his evolution at Juventus and Madrid.
"It is like that. I don't think he can end with us."
Earlier, England striker Marcus Rashford scored twice with Marouane Fellaini, Anthony Martial and Henrikh Mkhitaryan scoring United's other goals in a one-sided victory in front of 25,667 fans.
New striker Lukaku was unable to get in on the goals after a 45-minute debut in the second half.
He missed one golden chance four minutes into his United debut, with his shot saved by Galaxy goalkeeper Brian Rowe. However, Mourinho was satisfied with Lukaku's "unselfish" display in leading the line.
"Lukaku is a target man, he plays with his back to opponents," Mourinho said. "A good thing today for me is to see that he's a team player. He's not selfish. He's not obsessed with goals.
"He was not that worried about himself, he was worried about the improvement of the team."
Rashford meanwhile reminded Mourinho of his eye for goal with a confident first-half display.
The teenager opened the scoring after only two minutes, punishing an error from Ariel Lassiter near the Galaxy penalty area to dart in on goal and place his finish beyond goalkeeper Jon Kempin.
The 19-year-old doubled his tally in the 20th minute, latching onto a clever pass from Juan Mata to make it 2-0.
Mourinho later revealed that Rashford, who looks to have added a physical dimension to his game, was still growing.
"It's just the natural evolution of a kid," Mourinho said. "He's already taller than when I arrived 13 months ago. He's three centimeters taller.
"He's put on some muscle but without any kind of specific work because his speed is his most important quality and we don't want to lose that."