The Norwegian striker, who limped off in the weekend win over Bournemouth, and looked set for a spell on the sidelines.
Instead, he started the game against the Swiss champions, scoring a brace to take his tally to 16 goals in 15 Champions League games for City since he joined the Club.
He also now has 15 goals this season in all competitions and looked sharp throughout, before being rested just past the hour-mark.
“I didn’t even speak with him,” Guardiola revealed.
“Yesterday, I saw the training session, how he moved and happy he was, and he felt good, so I said okay.
“For us, Erling is so important with his threat. He felt good so okay he’s going to play.
“After the job was almost done (against Young Boys), take a rest for Sunday.”
After Haaland converted a first-half penalty, he added a second six minutes into the second-half with a superb rising shot from the edge of the box – a goal that the City boss admits was a pleasant surprise.
“Yeah normally he scores from the six yard box and the penalty spot,” said Pep.
“He has this talent and it’s not the first time he’s done it.
“The action for Rico was amazing. Phil and Rico attack and I love when we attack in the final third making diagonal passes and break the movement of the opponents.
“Erling has the ball here and the goal is there and in that position, when he doesn’t think much and shoots, he is clinical.
“It was a fantastic goal and the second one from Phil was amazing, too.
“His control and finally, he didn’t shoot strong, he put the ball in the net softly.
“Always in the early ages when you are 6, 7, 8 years-old, he always had this type of finish and today it was back.
“You don’t need to shoot strong there, just put the ball close to the post where the goalkeeper can’t get it.
“He made an incredible action, the pass from Jack was perfect, the control from Phil was amazing.
“Two beautiful goals.”
