Manchester City are playing right now against Crystal Palace which is defending with 7 players and sometimes with the whole team, yet Grealish managed to score a goal after VAR verification.
Grealish knowing that there is now competition for his place in the team is making sure he impresses the coach now while he has the opportunity to before Jeremy Doku returns.
Chelsea in their own game against Sheffield have lacked the creativity to create enough chances to score. The game is drawn in the first half, and with less time to play now, Chelsea would have a bigger problem if Sheffield scored the first goal because they have defended well so far and will try to defend more better if they can score a goal. I suspect that Nkunku will have some time to play in this second half, if he scores if given a chance, that will be a good way to make his return.