Ferguson's side had too much quality for Boothroyd's Watford
Sir Alex Ferguson praised the grit of his Manchester United side after the 4-1 FA Cup semi-final win over Watford.
United had to reshuffle after defender Rio Ferdinand went off injured and Ferguson said the win was as good as the 7-1 Champions League win over Roma.
"It was a fantastic performance," said United boss Ferguson.
"It was as good as Tuesday in terms of the endurance, the courage, accepting the disappointment with Ferdinand when we had to change the team."
He added: "It was absolutely magnificent, I was so proud."
United winger Cristiano Ronaldo was again on the scoresheet and Ferguson praised his goalscoring exploits as well as the contribution of strikers Wayne Rooney and Alan Smith.
It wasn't as one-sided as the scoreline suggests
Watford boss Aidy Boothroyd
"Wayne Rooney had his best game of the season, he was absolutely fantastic," said Ferguson.
"Alan Smith has brought a breath of fresh life to the team. He is doing fantastically for us.
"It was Cristiano's 21st goal and he could go on to score 25, the form he is in."
United legend Denis Law paid Ronaldo the ultimate tribute of putting the Portuguese star on a par with United legend George Best.
"The way he's playing he could go on to become United's greatest player. He's so exciting," Law told BBC Five Live's Sportsweek.
"And when you have Rooney with him as well, that's a formidable duo. They could go on and win everything.
"It's very difficult to compare Ronaldo and George Best, but if Bestie played in this team, they'd be on a par."
Law added that he believed United could win three trophies this season.
"This team has got everything. There's a great chance they can do the Treble," he said.
"They're in the final of the FA Cup, I think they're a certainty to win the league so it's a matter of if they play well in the Champions League semi-final against Milan."
Watford boss Aidy Boothroyd believes the scoreline flattered United.
"They were just too strong for us and we didn't take our chances when we had that great little period in the second half," he said.
"It wasn't as one-sided as the scoreline suggests."