The Boro boss is hoping the DR Congo international will be fit enough to play a part against the Robins at Ashton Gate
The forward could not complete the Boro’s draw against Reading on Saturday after suffering an injury in the encounter.
Assombalonga has been a key member of Middlesbrough since teaming up with the side in the summer of 2017 from Nottingham Forest.
The 27-year-old has scored more than 40 goals across all competitions and this season he has featured six times for the Riverside Stadium outfit.
Last season, the Democratic Republic of the Congo international scored the only goal of his side as they lost against the Robins.
Warnock hopes the forward will pass a late fitness test to feature at Ashton Gate, but also open to improvising should the attacker not ready for the game.
“I won’t know until after training today. Britt’s having treatment this morning as he’s a bit sore,” Warnock told the club website.
“He’s been taking a battering from the centre-halves and we can’t afford to lose him or Chuba [Akpom]. With only having two strikers we’ll have to look at different options at times like we did in the second half at the weekend.
“I’m just getting with what I’ve got. If we only have one striker we will have to look at what we have and adapt accordingly. We’ll have a session in the morning and see what’s what.”
Middlesbrough are currently 15th on the Championship table with six points from five games and a win at Ashton Gate could see them move to the seventh spot.
Despite his eligibility to play for England, Assombalonga snubbed the European side to commit his future to the Democratic Republic of the Congo.
The centre-forward has eight caps for the African country since he made his international debut against Tanzania in 2018.