The Norwegian forward was substituted in the final moments of the weekend's victory over Eddie Howe's team after injuring his knee during the buildup to City's last goal, scored by James McAtee.
Haaland played a key role in the goal, providing a vital flick-on from the near-post off an Ilkay Gundogan corner. McAtee then met the ball at the back-post and fired it home from close range. However, it appeared Haaland injured his knee when landing and, after the restart, he collapsed to the ground without any challenge.
With the 24-year-old clutching his knee in pain, many feared the worst. The scene brought back memories of Rodri's knee injury last September, which ultimately led to the Spaniard suffering an anterior cruciate ligament tear and ending his season early.
As the Premier League champions enter a pivotal stretch of the season, including their upcoming clash with Real Madrid in the UEFA Champions League round of 16 on Wednesday night, the focus shifted to Haaland's condition after the match ended.
Those present at the Etihad Stadium on Saturday noticed the stand-in captain walking comfortably around the pitch post-match, shaking hands with officials and celebrating the win, smiling throughout.
During his post-match media conference at the Etihad, Guardiola was asked about Haaland's injury concerns, to which he responded, "When he was down, everyone was scared."
The manager added, "He got up, walked, smiling as usual. I didn't speak to him, but the doctors didn't give any bad news. Hopefully, he will be fine for Real Madrid."
It was a notable day for Haaland, who wore the captain's armband for the first time in a competitive match, marking another milestone in his growing career at the club.
Guardiola revealed that he had personally chosen Haaland to join the first-team leadership group following Kyle Walker's departure, telling reporters, "Erling has signed a 10-year contract, so I have the feeling about him as captain. I am really happy for him."
The extent of Haaland's injury will become clearer after further assessment when the squad returns to the City Football Academy for recovery on Sunday morning.
Guardiola is also set to speak to the media again on Tuesday as his team travels to Madrid for the crucial second leg of their Champions League round of 16 clash, trailing 3-2 from the first leg.
Manchester City secured a second successive Premier League victory at home against Sunderland, Chelsea were held scoreless away to Bournemouth while Tottenham managed to beat Brentford.
Manchester City manager Pep Guardiola insists his side are moving in the right direction as they continue to evolve following an off-season of significant rebuilding.
Fabian Schar has acknowledged the difficulty of adjusting to life outside Newcastle United's starting XI after a period of sustained importance to the side.
Pep Guardiola admitted he "did not have an answer" for Manchester City's collapse in a chaotic 5-4 victory at Fulham on Tuesday night.
