City travel to St Mary's sitting in third place on the Premier League table, with a win strengthening their Champions League qualification chances.
Guardiola insists there'll be no underestimating relegated Southampton on their own turf.
He said on Friday, "We start at 0-0. It's a massively important game for us. It's the beginning of three very important games.
"We will show full respect to them."
Kovacic at a really good level
While delighted with their run of results, Guardiola disagreed that his team are currently showing their best form for the season.
"In terms of results, yes," he continued, "though we did the same at the start of the season.
"But I know we can play better."
Guardiola also took the opportunity to praise Mateo Kovacic, who he says is now playing at "a really good level".
"The advantage he is playing alongside Bernardo (Silva), Gundo (Ikay Gundogan) and Nico (Gonzalez). He's showing a really good level of play."
Haaland will start at Southampton
Guardiola also announced Haaland is fit to start tomorrow.
"He's fit. He's fit. He's ready to start tomorrow," declared the manager, while also delivering an update on midfielder Rodri.
"He's still not available".
Meanwhile, Guardiola commented on Haaland's claims that City's players lacked the "hunger" they showed last season.
"Look, if he feels like that, then the players need to discuss it amongst themselves.
"We can do better (they know that). We doing better now, but it's only for a few weeks. We need to sustain that (form) for many, many months.
De Bruyne at a Premier League rival?
Guardiola was also asked about departing midfielder Kevin de Bruyne and the prospect of the City great signing for a Premier League rival.
Shaking his head, Guardiola insisted: "No, no. I just want the best for Kevin. I want the best for his family."
Nico O'Reilly in midfield
Before signing off, Guardiola had some positive words for Nico O'Reilly, admitting the youngster has made a major impact this season.
"He has played a lot of minutes and he has been outstanding.
"He is still learning and seeing what he can do better. But everything is fine and he making a regular impact in the team.
"I'm absolutely happy with the way he's stepped up. The results without him would be difficult to imagine."