LONDON: Arsenal needed only 12 second-half minutes to blow Watford away 3-0 and move second in the Premier League on Saturday with a display of firepower that had manager Arsene Wenger purring.

"In the second half we were relentless and when we scored we continued to go and it was a convincing win," Wenger, whose side have bagged 11 goals in their last three league games, said.

After being matched by Watford in the first half at Vicarage Road, Arsenal cut loose with talisman Alexis Sanchez, substitute Olivier Giroud and Wales forward Aaron Ramsey all on target.

With the pacey Theo Walcott also providing a central threat, Wenger's decision not to invest in a new striker during the close season is being vindicated -- even if Danny Welbeck will be out until January as he recovers from knee surgery.

While Arsenal have an enviable array of creative talent, Sanchez is irreplaceable, which is why Wenger holds his breath every time the Chile striker jets off for international duty.

He scored three goals in World Cup qualifiers against Brazil and Peru during the international break and arrived back with a sore hip, but Wenger opted to risk him against Watford.

"I did (think about leaving him out)," Wenger said of the striker who has burst back into form after a sluggish start to the campaign following a tough Copa America campaign.

"Yesterday in the training session he looked quite sharp and the medical people told me he has no problem at all, then I thought I would test if he is ready and if he was not ready I would take him out.

"When a player is on a scoring moment then sometimes the flow can be disturbed. That is why I left him in."