Red Bull boss Christian Horner plans to outwit Ferrari this weekend at Monaco by changing the team's pitstop strategy.

Horner said he believes Ferrari copied Mark Webber's pitstops in Spain last week, like-for-like bringing in Fernando Alonso each time as that was the only way they could beat Webber.

He said they had changed their procedure to be less transparent.

Webber is hoping to recapture the form of last year's Monaco which he won, while team-mate Vettel is aiming for his fifth win this season.