Guardiola to make late call on Aguero
Manchester City take on the Bundesliga side on Tuesday having lost their first Group F game at home to Lyon.
Aguero, City's record goalscorer, has been carrying a foot problem but has travelled to Germany with the squad.
And Guardiola indicated he will give the Argentina attacker as much time as possible to prove his fitness.
"Tomorrow [Tuesday] is such a big game and Sergio is here because the doctors said he is able," Guardiola told a news conference.
"Tomorrow we will decide whether to play him or Gabriel Jesus.
"[Fabian] Delph, no. Benjamin Mendy maybe [available to play Liverpool on Sunday] - we have enough days until the game so hopefully.
"The problem is that they still didn't train with us, so hopefully when we return they can train with us."
PEP: We have five finals ahead in the Group Stages. Tomorrow is the first final.
Like Vincent said perfectly, it’s a top quality competition, it’s so complicated for all of us and we try to be stable. I think we are making steps forward.
— Manchester City (@ManCity) October 1, 2018
City received a boost with Kevin De Bruyne returning to training earlier than expected on Monday.
The Belgium star will not be available to play Hoffenheim and Guardiola is cautious over rushing his playmaker back to action.
"Today was his first training session back with the team so we will see when he's ready to play."
KOMPANY: I would love to win the #UCL with City, but I’m realistic and it’s so tough. Across europe there are six or seven other teams that are thinking the same. We have to deal that we lost to Lyon before we think of winning the competition.
— Manchester City (@ManCity) October 1, 2018
Speaking before Guardiola at Monday's news conference, City captain Vincent Kompany hailed the returning De Bruyne.
"It's difficult to quantify how much of a loss he has been," Kompany said of his compatriot. "He is one of the best midfielders, we get more goals and assists with him.
"Luckily we have players to fill the gap. He has a huge presence and you don't find it anywhere else in football."