Manchester United co-owner Sir Jim Ratcliffe says fans “have to be a bit patient” following his investment in the club.
Ratcliffe completed a £1.25bn deal to buy a 27.7% stake in United in February.
The 71-year-old said he was “about 10 km” into rebuilding the club, who are currently seventh in the Premier League.
“It’s a long journey,” he said. “The fans are impatient and I have some sympathy with that.
“It’s a journey and people, whether they like it or not, have to be a bit patient.”
Ratcliffe was speaking to BBC Sport on Sunday after running the London Marathon and before travelling to Wembley to watch United’s FA Cup semi-final against Coventry City.
The Red Devils reached the final despite having thrown away a three-goal lead as Championship side Coventry forced extra time.
But Erik ten Hag’s men eventually came out on top to win 4-2 on penalties.
British billionaire and boyhood United fan Ratcliffe also expressed frustration that new recruits have not been able to start work yet.
“We’ve got these new guys to come into the team, capable people, but they’re all on gardening leave,” he said.
“So it takes you six months, a year, 18 months before they can join. It’s a real issue in football.”
United will face local rivals and holders Manchester City in the FA Cup final and Ratcliffe said his side will be “definite underdogs” against Pep Guardiola’s men, who beat United in last year’s final on the way to a historic Treble.
“It’s not a light switch. You can’t just turn it around like that it takes a bit of time,” he added.