Brisbane Roar are anything but certainties to claim a third straight A-League title based on the opinions of rival coaches, who have struggled to nominate a standout favourite for the new season.

With the Roar's campaign for a championship hat-trick commencing this weekend as season eight kicks off, a big question mark hovers over their title hopes following the departure of coach Ange Postecoglou.

While most coaches predict the Roar to remain a potent force under promoted former assistant Rado Vidosic, only two of nine coaches polled by AAP at Tuesday season's launches were willing to single them out as the biggest title threat.

With Postecoglou's move to Melbourne Victory, the signings of marquee stars Alessandro Del Piero (Sydney FC) and Emile Heskey (Newcastle), and the arrival of Western Sydney Wanderers throwing plenty of spanners in the works, most coaches preferred to sit on the fence.

The Roar, Central Coast and Perth were predictably talked up as title hopes but many would not write off the likes of Sydney FC and the Victory.

Even, Postecoglou, the mastermind of the Roar's dominance in recent years, predicted the title race was wide open.

"I don't see anyone dominating it," the new Victory mentor said.

"Obviously Brisbane dominated the year before and Central Coast, to a certain extent, both teams dominated the landscape.

"But I have a feeling it will be throw a blanket over the whole group.

"At this point in time, there are probably 10 clubs who all believe they're a chance and I think that's realistic."

Newcastle's Gary van Egmond and rookie Melbourne Heart coach John Aloisi felt the Roar were the team to beat again, saying Vidosic's promotion from within would hardly rock the boat.

"Rado knows what has been going on, so I don't see there being too much change in the way they play," van Egmond said.

The coaches were more forthright over potential dark horses, with Adelaide United and van Egmond's Jets emerging as candidates to become surprise title contenders in 2012/13.

Glory coach Ian Ferguson was one of three coaches who thought the Reds could transfer their strong Asian Champions League form to the domestic league under John Kosmina.

"What Kossie has done there is come in and give them a little bit of bite about the team," Ferguson said.

Mariners coach Graham Arnold and Sydney FC's Ian Crook both predicted NSW rivals the Jets could prove the surprise packets under 2007-08 championship-winning coach van Egmond.

"I think the way Dutchy had them playing last year, towards the back-end of the year, they pretty much just missed an out-and-out number nine and I think they've got him (in Heskey)," Arnold said.

Del Piero, Heskey and Western Sydney Wanderers' Japanese recruit Shinji Ono on Tuesday all declared themselves fit for this weekend's opening round, though it's likely they will be used sparingly ahead of long campaigns.

Italian great Del Piero was not sitting on the fence when asked if he could claim some silverware in his first season with the Sky Blues.

"I believe we will (win the title)," the 37-year-old said.

"But I know it's not easy."