HAWTHORN'S last-gasp two-point loss to Essendon confirmed something coach Alastair Clarkson already knew: the two-time reigning premiers aren't unbeatable.

Some pundits were all but ready to hand the Hawks a third successive premiership after their 62-point dismantling of arch-rival Geelong in round one, but Clarkson said nobody at the club believed the hype.

"The whole football world has got Hawthorn as being unbeatable. We know within the four walls of our club that we're not," he said after the gripping loss to the Dons. 

"We need to produce our best effort to get results each week and we didn't bring our best effort today.

"That's why ultimately Essendon was able to move the ball far too easily. They had 430 possessions; you're not going to lose too many games of footy when you touch the ball that often." 

WATCH: Clarkson on Hawthorn's 'worst half of footy' in a long time

Despite a first half littered with skill errors and poor decision-making that was atypical of the Hawks of recent seasons, Clarkson's outfit nearly snatched victory over the tiring Bombers at the MCG on Sunday. 

Jack Gunston's three-goal burst after the main break ignited the flat Hawks, who surged from 17 points down to a 16-point lead midway through the final term. 

But a stunning three-goal burst from Jake Carlisle, Travis Colyer and unlikely hero Cale Hooker clinched a famous victory for Essendon, who saluted on a day when the club celebrated its back-to-back Grand Final triumphs over Hawthorn in 1984-85. 

Clarkson said his team should never have been in the match after their dismal opening half, but then should never have coughed up what seemed to be a match-winning lead. 

"So (I have) mixed emotions but mainly disappointment with the first half and not giving ourselves a decent enough chance to apply any scoreboard pressure early," he said.

"We've played some good footy for a long, long period of time and we just managed to play our worst half of footy for some time.

"We're disappointed with it and we'll be better for the loss, in a sense."

Unexpectedly 1-1, the Hawks face a rejuvenated Western Bulldogs side coached by Clarkson's former protégé and backline coach Luke Beveridge in Launceston in round three.

"We're all competitive beasts and we hate to lose. Is that the spur (for our season)? I don't know," Clarkson said.

"We've got a tough opponent next week in the Western Bulldogs who have been playing some really good footy. 

"We go to Launceston knowing full well if we produce anything like we did in the first half next week then we're probably going to finish up second next week. 

"So we've got some work to do."

The Hawks are likely to be without key defender James Frawley (pectoral) in round three after he was substituted out of the match against Essendon.

However, late withdrawals Josh Gibson (soreness) and Sam Mitchell (corked calf) are chances to come back into the side.