Phil Foden is expected to feature at the Pirelli Stadium, while young defenders Philippe Sandler and Eric Garcia have also trained with the first-team in recent days.
Guardiola said: "I'm pretty sure they are motivated to play in the first team, to play alongside incredible players in competitions and semi-finals. Of course, they are going to be motivated.
"But they have to know how difficult it is to achieve [a place in] the first squad and the first team, not just in Man City but everywhere.
"It is a massive opportunity for them to be close to the first team but it is not easy. We don't give presents because they are nice or something special. It depends on them.
"They have to show us, they have to play their level. Wednesday is a challenge for them but I'm pretty sure they are going to play good because they can do it."