The Citizens - who have lost their last two games - were already coping without Rodri (ACL) and Oscar Bobb (leg) and have now lost Jack Grealish, Ruben Dias and John Stones to unspecified problems.
The City boss was at least able to welcome Kyle Walker, Jeremy Doku, Savinho and Kevin De Bruyne back to the ranks for Saturday's 2-1 defeat to Bournemouth, although the latter two were only unused substitutes at the Vitality.
De Bruyne and Savinho's no-show raises questions about whether they will be fit to start Tuesday's game, where Walker is an obvious candidate for the chop as Rico Lewis seeks a recall to the XI.
Guardiola's hand is otherwise forced in defence, where Manuel Akanji, Josko Gvardiol and Nathan Ake will shield Ederson once more, while Mateo Kovacic, Bernardo Silva and Ilkay Gundogan should reprise their roles in the middle.
A fit-again Doku is an option to step in for Phil Foden, though, while the increasingly influential Matheus Nunes could continue in his new role on the left-hand side in support of Erling Haaland.
The latter needs just one goal or assist on Tuesday to reach 50 Champions League goal contributions in just 43 games, which would be an all-time record; Ruud van Nistelrooy is currently the quickest to hit a half-century, doing so in 45 matches.
Manchester City possible starting lineup:
Ederson; Lewis, Akanji, Ake, Gvardiol; Silva, Kovacic, Gundogan; Doku, Haaland, Nunes