Winger Tomas De Vedia scored four tries as Saracens put Narbonne to the sword in their European Challenge Cup clash.

The win takes Alan Gaffney's men to the top of Pool Two and a guaranteed spot in the final eight, but they will be looking for a bonus-point victory at Glasgow next Friday night to ensure a home quarter-final.

The Vicarage Road crowd barely had time to find their seats before some good handling from England hopeful Andy Farrell put De Vedia over in the corner in the second minute.

Glen Jackson added the extras from the touchline and fans settled in for a try-fest.

Narbonne showed they came to play by camping in the Saracens' quarter for the next 10 minutes, but had only a penalty goal to show for it when De Vedia broke clear to score his second.

Backrower Ben Russell made it three tries after visiting prop Luc Ducalcon was sin-binned for foul play, and Farrell's brilliant pass gave De Vedia his hat-trick and Saracens a bonus point before half-time.

Russell completed a double in the opening exchanges of the second half, Dan Scarbrough was over next and De Vedia bagged his fourth before Narbonne dug deep to score three tries in the final quarter.