BMC's Drucker out-sprinted German Rudiger Selig to win the 156.4km stage from Alcaniz to Peniscola.
Team Sky rider Froome finished in the peloton, alongside Quintana, and stays three minutes 37 seconds adrift.
A win for the Briton would make him the first to win the Tour de France and Vuelta in the same season for 38 years.
The race, the third Grand Tour of the season, has a rest day on Tuesday before resuming on Wednesday with five stages remaining.
Froome will expect to gain time on Colombian Quintana in Stage 19's individual time trial on Friday, as he bids to win his first Vuelta a Espana.
