Saturday saw the spotlight fall on United greats past and present as Rooney netted his 249th goal for the club early in the FA Cup third-round match against Reading.
The 31-year-old’s name echoed around Old Trafford as supporters celebrated, with Charlton fittingly chief among them after his long-standing club goals record was matched.
It is a matter of when rather than if Rooney usurps the World Cup winner’s scoring feats, just like he did with England, and set a record that it would appear difficult to challenge in the modern era.
Mourinho believes it will be tough to get near but has seen enough in 19-year-old Rashford to think he could go close.
“I don’t know the distances, really, but I think the ones that are close are players that left United already,” the Portuguese said.
“So, especially modern football I see really difficult. I don’t know, who knows?
“Marcus, he is 19. If he plays Man United until the end of his career, maybe Marcus can do it but Rooney scored a lot of goals.”
The fact Rashford is even being mentioned highlights just how highly the attacker is rated by United.
The 19-year-old only made his debut late last February yet has already netted 14 times.
There had been a slump of late but Rashford’s return to the starting line-up brought a brace in Saturday’s 4-0 win against Reading — his first goals in 18 United matches.
“I spoke with him at half-time,” Mourinho said. “I told him that I don’t care with the goals he missed in the first half because he had big responsibility in the way we were breaking their defensive line.
“He was playing so well for us. One more goal, one less goal — it doesn’t change. But obviously for an attacking player to score a goal means happiness, means confidence, so it was good for him.”
Despite Rashford grabbing two, the striker was well aware in his post-match interview that Saturday was about one man.
Charlton actually scored 251 goals for United but the club doesn’t deem his brace in an Anglo-Italian Cup tie against Verona to have come in a first-class game.
So Rooney’s 249th goal on his 543rd competitive appearance for United was a historic moment that led onlookers to wonder how high a bar he could set.
Asked how long Rooney has left at the top, Mourinho said: “I don’t know, it depends on him, especially on his brain, on his desire.
“I think everything is about desire, more important than anything else, so I think he has motivation so if he keeps motivation he can play.”
The United boss added: “When they take good care about themselves, when the wives help, when they train well, when the manager and the staff is intelligent enough to understand the difference between the body of a teenager or the body of a man of 30-something — when there is a combination of factors, they can delay the end of their career.
“That’s why we have Michael (Carrick), Zlatan (Ibrahimovic) and Wayne performing.”
Rooney could be at the club until 2019 if the additional year in his deal is exercised — not that Mourinho has thought about how long he has left.
“I don’t even know his current deal,” the United boss said with a laugh when asked about Rooney seeing out his deal at United.
“I am not worried with my players’ contracts. I leave this to Mr Woodward (executive vice-chairman Ed Woodward) to deal with.”
Mourinho, whose side face Hull in the EFL Cup semi-finals tomorrow night, added of Rooney: “I always had a good feeling with him — a good professional, a team player. I saw him always sacrificing for the team.
“He played against me when I was in Real Madrid in Madrid. He played almost left-back. I always saw him sacrifice for the team and with me he is the same.
“He is on the bench, he comes in. He plays, he doesn’t play, but always positive with the group, a good captain, so I am really happy.”
Romero, Young, Smalling, Rojo (Jones 19), Blind, Fellaini, Carrick (Fosu-Mensah 78), Mata (Schweinsteiger 78), Rooney, Martial, Rashford.
Pogba, Ibrahimovic, Mkhitaryan, Joel Pereira
Al Habsi, Gunter, Liam Moore, van den Berg, Blackett (Obita 46), Williams, Evans (Swift 57), McCleary, Kelly, Beerens, Kermorgant (Samuel 77).
Cooper, Meite, Watson, Stuart Moore. Referee: Andre Marrine.