The City boss revealed that Haaland received a kick in the first half and was taken off as a precaution with City three goals ahead going into the break.
He will be checked out over the next few days ahead of the table-topping clash with Arsenal on Wednesday night.
“Erling has a kick and we will see,” Guardiola said. “We will assess him in the next few days to see how severe it is.
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“At half-time I spoke with the doctors to see and they said maybe at 3-0 we don’t need to take a risk and I agreed with the doctors.
“If the score was more tight maybe I wouldn’t do it. I think he’s not injured but tomorrow we will see. Hopefully he can play there on Wednesday. If he’s not ready or it’s a risk he’s not going to play.”
WATCH: Guardiola: It was important to close gap on Arsenal
Meanwhile, Dias was replaced after picking up a yellow card with Guardiola not wanting to risk a second with Villa’s threat on the counter-attack.
The Portuguese international was making his first City start since playing at the World Cup after working his way back to full fitness and should be in contention to face the Gunners.
“Ruben [was substituted] because it was a yellow card,” the boss said. “Of course, he was disappointed but unfortunately he got a yellow card - I don’t know why but it is what it is.
“With [Ollie] Watkins and [Leon] Bailey they have good runners in behind so we decide to not take risks with the score at 3-0.”
Victory moved us to within three points of Arsenal with the chance to go top of the Premier League with a win at the Emirates Stadium.
While it’s a huge match, Guardiola is expecting no easy games between now and the end of the season but is confident that his side will travel to London with confidence.
“Today I had the feeling that every game will be so difficult,” he added. “The players at the bottom of the league are fighting for so many things. Every game is tougher and tougher.
“We will travel to London to play our game.
“Especially the way we are behaving in the training sessions in the last week to 10 days, we improved a lot.
“Everyone is so focused, not just the performances. You have to have the chance to be competitive - that doesn’t ensure you will win, but without that it is impossible.”
