Stones scored City’s opener in the 50th minute on Wednesday night and marshalled the rearguard with Ruben Dias to repel United’s attacks before Fernandinho sealed the victory seven minutes from time
Guardiola’s side, who are in the final for a fourth consecutive year, will play Tottenham Hotspur on 25 April at Wembley.
"All credit for John,” said Guardiola. “In a long career, you always have ups and downs. Unfortunately, he struggled longer than we expected and he expected - but his comeback is absolutely down to him.
“The most important thing he has been able to do - something he has struggled with the past three or four years - is play four, five, six games in a row. This is so important.”
Resurgence
Stones moved from Everton to Manchester City in the summer of 2016 for 56 million euros.
But injuries undermined his form and he dropped down Guardiola’s pecking order amid rumours he might leave the club.
Stones attributed his resurgence to hard work. "I'm trying to play as many games as I can,” he told Sky Sports after the match.
“Staying true to myself, to what I can do and what I can improve on. Playing in these big games is something I thrive off, the team thrives off. I'm trying to improve as much as I can.”
City will seek to equal Liverpool’s record of four consecutive titles when they play Spurs who have not won a trophy since they lifted the League Cup in 2008.
