ST KILDA will enter Sunday's clash against Carlton with depleted key position stocks after forward Paddy McCartin and defender Hugh Goddard left the field on stretchers in separate incidents against Adelaide.

McCartin went to hospital after a nasty collision in which he clashed heads with teammate Jack Newnes, only to hit his head against Crows defender Luke Brown before hitting the deck.

The third-quarter incident was McCartin's second concussion for the year, with the 20-year-old experiencing a similar injury against Collingwood in round three.

Goddard, meanwhile, suffered a suspected ruptured left Achilles tendon in the second quarter as he pushed off his leg in an innocuous incident.

Compounding matters, defender Sean Dempster came off the ground early in the third term with an apparent right hamstring complaint, but returned to the field.

Skipper Nick Riewoldt was involved in a knee-on-knee collision with teammate Tom Hickey in the opening seconds of the game but he, too, battled through the match and will have scans on Monday to determine the severity of his knock.

The latest injuries come at the worst possible time for the Saints, who are already without ruckman Billy Longer (concussion) and defender Sam Fisher (hamstring) for extended periods.

Western Bulldogs youngster Toby McLean injured his right ankle in the second quarter against West Coast and did not reappear after being assisted off the ground. 

Bulldogs big man Jordan Roughead was left dazed after receiving a head-high bump from Eagle Shannon Hurn. 

Essendon tagger Ryan Crowley walked off the ground with a right hamstring injury he sustained in the final minutes against his former side.

The 32-year-old received a standing ovation from the Fremantle crowd in a sign of respect as he limped off.

Richmond is counting the cost of a horror night on the injury front, with four players going down against North Melbourne on Friday night. 

The Tigers' woes started with defender Dylan Grimes injuring his right hamstring in the warm-up, forcing emergency Troy Chaplin to frantically pull on the guernsey. 

Fellow defender Steven Morris ruptured the anterior cruciate ligament in his right knee after landing awkwardly in a marking contest in the first term, and was taken off the ground on a stretcher. 

The Tigers confirmed the ACL tear on Sunday, which will sideline the 27-year-old for the next 12 months.

Backman Nick Vlastuin did not take any part after half-time because of a head knock he received after colliding into Roo Jarrad Waite's hip in the second term. 

The 22-year-old was assessed at the main break but failed a concussion test.

The Tigers then lost Ben Griffiths in third quarter with a badly sprained right ankle he suffered after landing on Drew Petrie's foot in a marking contest.

The 200cm forward, who will be closely monitored over the coming days, had to be taken off the ground on a stretcher.

North Melbourne's win was soured by a left ankle injury to defender Sam Wright early in the final quarter. 

The 25-year-old sustained the injury to the opposite ankle that sidelined him for three weeks between rounds seven and nine.

In other injuries at the weekend:

- Lion Allen Christensen collided heavily with Blue Andrew Walker late in the second quarter. The 25-year-old came off the ground with a broken right collarbone and was taken to hospital for surgery. Speaking post-match, Lions coach Justin Leppitsch said Christensen would have a plate inserted and miss at least the next month.

- Carlton ruckman Matthew Kreuzer felt "physically ill" at the main break, according to the Blues' Twitter account, and did not reappear after half-time against the Lions. Kreuzer received an accidental knock just below his right eye in a tackle, and experienced swelling and signs of concussion. 

- Hawk Jack Gunston spent an extended stint on the bench in the third quarter against Melbourne and played out the second half with a slight limp. The goalkicker's day ended slightly early due to the right leg/ankle complaint.

- Swan George Hewett did not return to the field after receiving a head knock as he laid a tackle on Sun Jack Martin in the first quarter. The 20-year-old will have his jaw further assessed and go through the usual post-concussion testing.

- Fremantle forward Michael Apeness fractured his left collarbone in the third quarter. The 21-year-old was involved in two separate collisions with Bombers skipper Brendon Goddard.

- Suns midfielder Jesse Lonergan's game ended prematurely with ice strapped around his right knee late in the last term. The 21-year-old initially had his knee heavily strapped after colliding knee-on-knee with Swan James Rose in the first term, but returned to the field. He will now have scans to determine the full extent.

- Suns captain Gary Ablett had his left shoulder assessed at the interchange area in the dying minutes of the clash against the Swans.

- Collingwood forward Jeremy Howe limped off the ground in the first quarter against Port Adelaide after landing heavily on his left leg, but managed to play out the game with the heavily strapped knee.

- Luckless Saints midfielder Nathan Freeman was withdrawn from Sandringham's VFL reserves match after experiencing hamstring tightness in his troublesome right leg at training on Friday. The 20-year-old, who has been plagued by hamstring setbacks, will now have scans to determine the severity of his latest setback.

- Geelong will be sweating on the fitness of midfielders Josh Cowan and Billie Smedts after the pair hobbled off the ground in the VFL on Sunday. The extent of both injury concerns remains unclear. 

- Power defender Alipate Carlile, who had recently recovered from a broken wrist, went down with a serious knee injury in the SANFL on Saturday and his year appears to be all but over.