Forwards were the major casualties in a nasty AFL weekend for some of the league's best goalkickers.

As Essendon was still coming to terms with how it will cope without full-forward Matthew Lloyd for the rest of the season, Adelaide and Melbourne were confronted with the likelihood of having their main focal points sidelined.

Crow Ian Perrie might not play for up to three months because of a posterior cruciate ligament injury to his left knee, which he injured when he crunched into the back of Fremantle's Luke McPharlin late in Saturday night's game at Subiaco Oval.

And Melbourne skipper David Neitz was on Sunday twice forced off the SCG with a hip injury, which prevented him from playing out the Demons' five-point win over Sydney.

Melbourne finished the game with only one fit player on the bench, as Paul Johnson (shoulder) and Brock McLean (groin) also suffered game-ending injuries, but could regain onball trio Phillip Read, Daniel Bell and Clint Bizzell.

Perrie's injury is a cruel blow for the Crows, who could next week be without both their leading scorers from last season, as Scott Welsh is still yet to return from a shin injury.

The Crows expect the best result for Perrie to be a two-week absence, but scans could show he might need to be sidelined for between eight and 12 weeks.

"It doesn't look good," coach Neil Craig said.

"But we are not the first club to get a major injury, and I am sure we won't be the last, so we push on.

"(Ian) has been an important player for us, he's been a really important player up in our forward line, he knows the system ... a good game knowledge of it, and has been able to impart that.

"We are not going to have him so that means other players are going to step up."

Even the victorious Western Bulldogs and Richmond were left with headaches over forwards in round four.

The Bulldogs had Brad Johnson (gastro) and Robert Murphy (ankle) below their best in Saturday's one-point win over Geelong, but both should play St Kilda on Saturday.

The Tigers face a far pricklier decision ahead of Friday night's game against Carlton, as Nathan Brown continues to be thwarted in his comeback from last year's serious leg injury.

Brown withdrew from last night's clash against the Brisbane Lions through leg soreness, and coach Terry Wallace admitted his star's treatment would be reassessed.

The Swans were also nursing injury tolls on Sunday, as half-forward Nick Davis injured a hamstring against the Demons, while Stephen Doyle suffered the same injury in the reserves on Saturday.

Geelong's injuries hit hard in the one-point loss to the Bulldogs, but the Cats should at least get fullback Matthew Scarlett back from suspension and possibly centre half-back Tom Harley back from a knee problem in time to play Sydney on Saturday night.

West Coast star Ben Cousins withdrew from Sunday's win over the Kangaroos because of hamstring soreness, but the Eagles expect him to play the Lions.

Lloyd will undergo surgery on Monday to repair his left hamstring tendon, which was torn away from the bone in round three.

The Bombers captain is expected to miss the rest of the season after being told by his surgeon there could be lasting damage if the tendon was not repaired.

"He said `You don't have to go through with the surgery, but I don't feel you'll ever be able to run the same if we don't do it', so I sort of had no option," Lloyd said.

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