The Red Bull Formula 1 team are reportedly considering alternatives to Renault due to issues with their power unit.
While the team have appeared to recover from the problems that dominated pre-season testing, adviser Dr Helmut Marko is said to have claimed that the unit is not up to scratch.
According to Bild, the reigning constructors' champions are considering other options should their issues with Renault not be resolved.
Red Bull are currently sixth in the standings following races in Melbourne and Malaysia.
