The pair were part of a group of seven players who have had to isolate recently after returning positive tests.
However, the latest round of testing brought some good news to a Chelsea side who have been below par in recent weeks.
Lukaku and Hudson-Odoi could return to training on Thursday if they return another negative test, and may be available for the boxing day trip to Aston Villa.
Manager Thomas Tuchel revealed the news after Chelsea defeated Brentford 2-0 in the Carabao Cup quarterfinals on Wednesday thanks to a Pontus Jansson own goal and a Jorginho penalty.
"If I understand correctly we a negative test first of all, and we had a negative test for Romelu and Callum and Ben Chilwell," said Tuchel post-match.
"Ben Chilwell will not be involved in the Aston Villa game and for the other two they will be on the pitch tomorrow if they test negative again. Then we need to see. The guys have been ill and had symptoms. So let's see.
"It's a Premier League game at one of the toughest places you can play. It's good news, don't get me wrong, but I'm not over-excited now because I need to check how they are."
Chelsea’s reward for beating Brentford is a two-legged semi-final tie with Tottenham Hotspurs, and Tuchel is relishing the contest with Antonio Conte’s side.
"It was always going to be a tough draw. Tottenham is nice for our fans. A London derby, we are looking forward to it and we want to be there," added Tuchel.
