European champions Bayern have expressed interest in signing Hudson-Odoi after previously trying to buy him last year.
The 19-year-old made his first Premier League start since February as Chelsea routed Crystal Palace 4-0 on Saturday.
Hudson-Odoi, who struggled with injuries and poor form last season, is understood to favour staying at the Blues.
Lampard has reiterated his desire to keep the youngster, but the Chelsea boss conceded he was not certain the England international would remain at Stamford Bridge.
Asked whether Hudson-Odoi will be at Chelsea beyond the deadline, Lampard told reporters: "There is no definitive answer. By Monday we will know the answer.
"They (Bayern) might have declared their interest, which is one thing, but as I have just said there in terms of the squad, everything that happens by Monday will be things that are firstly good for us as a club.
"Callum is our player and what Callum wants comes into consideration. It has to be right for everybody.
"At the minute I want Callum as part of my squad, especially with what he offered up today and the second half against West Brom. That is where I am at."
Hudson-Odoi signed a new five-year contract at Chelsea in September 2019.
But now the German champions have shown strong interest in him again, he could be tempted to leave given Lampard has Christian Pulisic, Hakim Ziyech, Mason Mount and Timo Werner all capable of playing on the flanks.
"I liked Callum's performance today, especially in the second half when he was more aggressive and getting at the full-back on the outside," Lampard said.
"Callum is absolutely part of my plans here. We have Pulisic and Hakim Ziyech injured before Christian came back in today."
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