HAWTHORN left the MCG on Saturday looking over its shoulder after a five-goal loss and a possibly serious pectoral muscle injury to key backman Ben Stratton.

Stratton injured the muscle in his left shoulder in the second term and didn't reappear after half-time, as the Hawks opted not to risk the defender.

WATCH: Alastair Clarkson's full post-match press conference

Coach Alastair Clarkson was hopeful the injury was not too severe, but admitted it had left his side undermanned in the shock 29-point loss to Melbourne.

"Stratts has got a little bit of a pectoral injury. We're not sure of the severity of it but we just didn't want to take a risk after half-time so we will get that scanned during the week and see what the outcome of that is," Clarkson said.

"It just meant we were a bit less stable in our back end than what we would like, which was the reason they (Melbourne) were able to go coast to coast on many occasions

After such a costly loss following nine successive wins, the Hawks now need to win their last three games to guarantee top spot.

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A game clear, but with an inferior percentage to most top-eight teams below them, each win is now vital.

"We've been pretty good for a fair period of time and hopefully it is just an aberration," Clarkson said.

"We'd won nine out of 10. There are 17 other clubs in the competition that wish they had that record."

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James Frawley – who missed the Melbourne match – is also under a cloud, battling what Clarkson described as a "grumbly shoulder". 

When the Hawks also wasted chances in front of goal, the Demons' spirit lifted.

"It's a game of momentum and spirit and taking your chances and confidence, so they took their [chances] today and they made us look silly at times," Clarkson said. 

He praised the performance of small forward Cyril Rioli who kicked four goals and was outstanding in applying 12 tackles and a bone-crunching bump that rattled but did not finish Clayton Oliver. 

"We would have been in a lot more trouble if we didn't have Cyril," Clarkson said. 

The coach would not comment on the bump beyond saying he didn't think there was much in it.  

The Hawks hope Rioli’s partner-in-crime in Paul Puopolo will return from a hip injury next week while Liam Shiels is also a chance to return after being out with a hamstring injury. 

"We come away from the game disappointed obviously but know there is still a hell of a lot to play for in the last month," Clarkson said.

With North Melbourne ahead next Saturday afternoon, the business end of the season has arrived for the Hawks.

"We're going to have to play a little bit better than we did today if we are going to challenge [North Melbourne] next week," Clarkson said.