ALASTAIR Clarkson is a coach who knows about accuracy and momentum.

In the 2008 grand final, Geelong had all the momentum in the second quarter but kicked badly. Hawthorn somehow went in at half-time with a slender lead and kicked on from there to win the flag.

Hawthorn yesterday had the momentum in the first half but kicked badly. Melbourne kicked straight and managed to go in half-time with a three-goal lead.

Clarkson was worried that, if the Demons had another run like their five-goal burst in the second quarter, they might have been able to take the match out of the Hawks' hands.

"(I wasn't) overly comfortable," he said. "All it takes in that situation is for Melbourne to start winning a few more clearances and a bit more contested ball; that margin can spread out a bit too much.

"Melbourne rely enormously on a lot of defensive transition goals, moving the ball from one of the end of the ground very, very quickly - relying on a mistake, a turnover and then a slingshot out the back.

"They did that quite frequently and we were unable to defend that very well. But in the second half we controlled the ball a lot more."

The Hawks kicked 8.11 to 1.1 in the third quarter to wrest the match their way. Clarkson made no particular positional moves, but there was one change that did have a cumulative effect.

Brent Renouf was subbed off early in the third quarter with concussion. Jordan Lewis came on and was creative around the forward line.

Just as significantly, David Hale and Jarryd Roughead took turns in the ruck and wore down Melbourne's Mark Jamar.

"Certainly it helped having another runner (Lewis)," Clarkson said. "The real twitchiness of that is you know when you activate your sub five minutes into the third quarter like we did, (then) you get another injury.

"It was like, well, we've got a fresh guy, let's get him on - we're not controlling the game and let's see if we get a change.

"Now is that the reason for the change? I know Lewis had a reasonable impact in the last 40-50 minutes of the game ... that was good, but Hale and Roughy, when they competed in the ruck, were really good for us.

"Certainly they made contributions, all three of those players.

"We don't usually like to activate the sub as early as that, but on this occasion it worked well for us."