Should Hawthorn fans be worried over their team's poor start to its AFL premiership defence?

That is the big question to emerge from the second round of 2009 as the Hawks became only the third reigning premier this decade to lose their first two matches.

While there are genuine reasons behind the Hawks' slow start to the season, primarily injuries to key players, history suggests Alastair Clarkson's team has to get its season back on track soon if it is to re-capture the heights of 2008.

The last reigning premier not to win its opening two rounds but rebound to win back-to-back premierships was Carlton way back in 1982 but at least the Blues of that year managed to draw in the opening round before losing in Round 2 and then finally winning in Round 3.

The only two other reigning premier to have lost their opening two matches in this decade - Sydney in 2006 and North Melbourne in 2000 - also got their seasons back on track by winning in Round 3 before going on to have strong seasons.

The Swans of course failed by just one point to win back-to-back flags in 2006 while the Kangaroos in 2000 were knocked out in the preliminary final that season by Melbourne.

In fact you have to go way back to 1976 to find the last time the reigning premiers (North Melbourne) lost their first three matches of the season and that year the Kangaroos would only win one of their first five games before staging a great fight back to win 14 of their last 17 games and eventually finish runners-up to Hawthorn.

So it's far from panic stations for the Hawks yet although there are some worrying signs.

The absence of Trent Croad, who is a long-term absentee with the serious foot injury sustained in last year's Grand Final, and last year's surprise packet in Stephen Gilham - whose knee injury sustained in the NAB Cup has seen him miss the first two rounds - has left the Hawks seriously short on height down back.

The ruck department also looks brittle with Robert Campbell a late withdrawal from the first two matches due to injury while Simon Taylor's two-match suspension for dropping his knee into Geelong's Joel Selwood in the opening round was unforgiveable and has left the Hawks reliant on youngster Brent Renouf to carry their big man department.

Throw in injuries to Jordan Lewis, Brad Sewell, Travis Tuck, Rick Ladson and Ben McGlynn and the Hawks' midfield suddenly lacks depth while the loss of tough small forward Michael Osborne in the opening round with a serious hamstring injury was another blow.

And Luke Hodge and Chance Bateman both looked sore during the loss to the Swans as even key players that are fit such as skipper Sam Mitchell and the hero of last year's Grand Final in Stuart Dew struggled to get into the game as Sydney overcame a slow start to crush Hawthorn by 38 points.

While the Hawks had almost walked away from their narrow Round 1 loss to a near full-strength Geelong as winners, such was the nature of their fantastic final quarter fight back considering the side they had at their disposal, the loss to the Swans raised questions as to whether the Hawks have totally recovered both mentally and physically from a gruelling 2008 season.

And with gritty Kangaroos to come on Easter Sunday, there is no let-up for the Hawks for whom the return of key players can't come soon enough.

Only when the Hawks have close to their full side available will we be able to make a definitive judgement as to whether they are suffering from the dreaded premiership hangover but a full side of mentally and physically fit players is something often denied reigning premiership teams coming off a gruelling season.

And there is no shortage of early challengers to the Hawks' crown with last year's runners-up Geelong unbeaten after two rounds along with the Bulldogs and St Kilda, who both appear to have improved since last year's losing preliminary final appearances, plus surprise packets Carlton.

On the evidence so far the Hawks' gun players can't return soon enough after their second-string side was exposed by the ageing Swans but even when their stars do return they will be lacking match fitness and Hawthorn might find they are giving sides such as Geelong, St Kilda, the Dogs and Carlton a considerable start before they begin to resemble the team that shocked Geelong by winning the 2008 flag.