First-half goals from David Barral and Nacho Cases set Sporting on the road to only their third league success of the season and brought to an end a run of 13 competitive matches without a win which had left the spotlight on long-serving coach Preciado.
Reports in Spain suggested a stoppage-time equaliser in last weekend's 1-1 draw at Racing Santander had kept Preciado in his job, but with just two wins in 30 matches stretching back to last season, the popular manager will have known the importance of getting a three-point haul against travel-shy Hercules today.
And he could hardly have asked for a better start as his men took the lead inside the opening 30 seconds through Barral.
Diego Castro's cross looked to be behind Barral but the former Real Madrid youngster did well to get his head on the ball and guide a header just inside Juan Calatayud's left-hand post.
That was just the start Sporting needed and Hercules would have been hoping to avoid as the visiting side sought to build on Monday's impressive 4-1 home win over Atletico Madrid.
Hercules have made a habit of causing major problems for La Liga's big guns this season, but most of their success has come at home as since they stunned Barcelona 2-0 at the Nou Camp in their opening away game, the promoted outfit have gone nine league and cup fixtures without an away win, scoring just three goals whilst conceding 17.
And the prospect of improving that poor run took a further turn for the worse when Esteban Vigo's side slipped 2-0 behind in the 30th minute against Sporting.
Cases was the scorer, picking up a pass from Miguel De las Cuevas before thumping a left-footed shot past the diving Calatayud from 25 yards out.
Hercules could find no way back after that as they slumped to their ninth defeat of the season, and they are now just six points ahead of Sporting.