City, who take on Nottingham Forest on Wednesday, will play six matches in all competitions in 18 days and Guardiola said he was confident in the abilities of Argentine Alvarez, who joined them from River Plate in the close season.
“When Erling doesn’t play, we will play Julian, almost sure. We’re really impressed with him, his pace, his sense of goal and his work ethic,” Guardiola told reporters.
“I knew him a little bit, off television, clips, games in River Plate. I was surprised at how good he is. He’s so humble, always positive. Every training session he gives everything. I like this type of player.
“He is… always close to the ball, has the sense to be in the position in the right moment. When he drops, he has the quality to play. I know people talk a lot about Erling but Julian is an exceptional player.”
Guardiola said he was also delighted with the progress of another new signing in Haaland, who has scored six league goals so far, including a hat-trick in their 4-2 win over Crystal Palace at the weekend.
“Everyone talks a lot, we’re delighted. Hopefully he feels good being here,” Guardiola said.
“I have another opinion, we didn’t have doubts, we only had one month of competition. We still have margins to improve to be a better player and we’re working on that.”
City are second in the league standings with 10 points from four games, while promoted Forest are 14th.