Lovenkrands has not recovered from the hamstring injury he picked up shortly after scoring his eighth goal in as many appearances in the 3-0 win over Preston last weekend.
The Dane is expected to be fit for next Saturday's home clash with Barnsley, as are Jose Enrique (hamstring) and Nicky Butt (thigh).
Routledge will miss out at Vicarage Road with a calf problem, and his fitness will be monitored next week.
Midfielder Joey Barton is back in training after a long-term foot injury, but is still some way off a return to action, while Shola Ameobi (hamstring) and Steven Taylor (medial ligament) remain on the sidelines.
