Holders Manchester City beat Chelsea 1-0 with a late Bernardo Silva goal on Saturday to reach the FA Cup final after an absorbing end-to-end Wembley semi-final left the exhausted winners still chasing a domestic double.
Silva sidefooted home in the 84th minute after Chelsea goalkeeper Djordje Petrovic parried a Kevin De Bruyne shot and that was enough to edge a hard-fought affair that left Chelsea boss Mauricio Pochettino waiting for the season to end.
City will meet Manchester United or second-tier Coventry City, who play on Sunday, in the showpiece game on May 25.
The result offered some consolation for Guardiola's weary team, who were eliminated on penalties in the Champions League quarter-finals by Real Madrid in midweek.
Portuguese Silva, who missed a penalty in the shootout defeat at home to Real, said he was: "Very happy after a very frustrating week for all of us, for me personally.
"The good thing is in football, if you play at Man City you play every three days, so after two to three days, you have a chance for a bit of revenge and to put things right."
City's win means they can lift another double, standing two points clear at the top of the Premier League, although they had to dig deep to keep their defence of the FA Cup on track.
"What they have done today was one of the greatest things I have seen in a group of players (after) 120 minutes against Madrid," said Guardiola, who bemoaned the tight turnaround time after the Real match, told reporters.
Chelsea, whose last visit to Wembley ended in League Cup final defeat by a late Liverpool goal in extra time two months ago, squandered some of the best chances.
Senegalese Nicolas Jackson was particularly profligate.
He had the first shot on target in the eighth minute but it was easily collected by Stefan Ortega in the City goal.
Early in the second half, Jackson had two chances to put the ball away but Ortega intercepted both.
There were also opportunities for 21-year-old former City forward Cole Palmer, who scored four goals against Everton in the league last Monday, and for Noni Madueke.
A last-gasp free kick from substitute Mykhailo Mudryk sailed over the bar, while Chelsea also had a penalty appeal turned down when Palmer's free-kick struck Jack Grealish's hand in the wall but VAR ruled in City's favour.
"In football the most important thing is to be clinical and to not concede," Pochettino, whose side face Arsenal in the Premier League on Tuesday as they try to make a late bid to qualify for Europe, said.
"We competed well, I cannot say we were the better side because that in football is difficult to measure. The most important thing is we competed."
Chelsea have now been eliminated from six of their last eight FA Cup ties against Manchester City, including in the third round last season.
