First cracks have appeared within the Brisbane Roar's A-League championship outfit following their dreadful start to the season.Tensions have risen within the Roar's dressing room following five losses from eight matches with senior player Erik Paartalu openly criticising coach Rado Vidosic's negative reaction to their 2-1 defeat to Central Coast on the weekend.Paartalu's attack also comes after talk of a bust-up between Vidosic and Mitch Nichols which resulted in the midfielder being dumped for their 4-2 win over Sydney FC almost two weeks ago.Assistant coach Jeff Hopkins on Wednesday admitted some relations were currently strained within an unhappy dressing room."It's not really a happy place but we're still a united place," Hopkins said."In any professional football club that is a couple of places off the bottom of the league then if it is a happy place then there's something wrong with the group."We all want the same thing. We want to get back on track. We want to work hard at getting more consistent performances."I'd be lying if I said everyone is happy. We're not happy, we're at the wrong end of the league at the moment."The two-time champions sit second last on seven points, 12 behind pace-setters Adelaide United, but still just one win from the top six.Since replacing Ange Postecoglou, Vidosic has enjoyed just two victories and a draw as head coach.But he only showed his frustrations for the first time on Sunday in blasting the Roar for being "naive" and "silly" against the Mariners.Vidosic also described the defending which led to Central Coast's late match-winner as kindergarten standard.Paartalu, among the leadership group at the club, took offence at the comments and called for more positivity ahead of Saturday night's clash with Newcastle."The defending wasn't great for the last goal but in times like this we all need to stick together," the midfielder told fourfourtwo.com. "So I think everyone needs to remember that - coach, manager, staff included."Blaming people, making accusations and negative comments isn't going to get anybody anywhere."We need to try and take the positives out of the game from the weekend and move forward as one."Hopkins defended Vidosic's comments and denied they were "over the top".