The Reds beat their London counterparts 2-0 at Anfield.
The Reds went into game on the back of a glorious 3-0 win over Villarreal on Thursday night to reach the Europa League final, but a 3-1 defeat at Swansea City seven days ago had put a downer on their end-of-season domestic form.
However, manager Jurgen Klopp fielded far more experience this time compared to the loss in South Wales, with Kevin Stewart and Sheyi Ojo being the only relatively inexperienced members of the first XI.
It was the resurgent Joe Allen who gave Liverpool a slender 1-0 half-time lead following an opening 45 minutes in which the Hornets had looked dangerous, but Roberto Firmino came off the bench to make sure of the victory on 76 minutes.
The Europa League final in Basle is just 10 days away, and former Reds winger Luis Garcia believes that victory is good preparation for their clash with reigning champions Sevilla on Wednesday week.