Adelaide coach Brenton Sanderson believes Marc Murphy's shoulder injury should be a warning to the AFL that tinkering with the slide rule could have dire consequences as players put their heads over the ball.

West Coast survived a major scare to hold off a fast-finishing St Kilda by 30 points at Patersons Stadium on Sunday, keeping them on top of the ladder for the seventh consecutive round.

Adelaide have underlined their premiership credentials through a 69-point thrashing of a rudderless Carlton on Sunday, with injury added to insult for the Blues as Marc Murphy appeared to seriously hurt his shoulder.

Daniel Merrett booted five goals in an explosive first-quarter performance as Brisbane cruised to a 92-point win over Greater Western Sydney at the Gabba on Sunday.

West Coast have been forced into a late change for Sunday's home match against St Kilda, with clearance specialist Matt Priddis ruled out with concussion.

Melbourne's horror season appears to have gone from bad to worse as reports have emerged that forward Liam Jurrah could miss a lengthy period of time with a suspected broken leg.

Richmond coach Damien Hardwick said his side simply ran out of legs in the final quarter of Saturday night's loss to Essendon in the Dreamtime clash at the MCG.

Geelong have re-signed Travis Varcoe and Mitch Duncan until the end of the 2015 season.

Essendon could be forced into a number of changes next week after Saturday night's bruising encounter with Richmond.

Sydney coach John Longmire has praised his side's desire and willingness to get on with the job after their crushing 101-point win over a hapless Melbourne on Saturday night.