Mar.27 (GMM) The pressure is continuing to mount on the shoulders of Felipe Massa, as observers chide his driving errors so far in 2008.



"A chain is only as strong as its weakest link, and Ferrari's is Felipe Massa," Sir Jackie Stewart, after watching the Brazilian driver terminally spin his Ferrari in Malaysia, told the Swiss publication Motorsport Aktuell.



There is some lingering doubt about the cause of the 26-year-old's Sepang retirement, but a Ferrari spokesman on Wednesday ignored a request to clarify whether or not Massa made a simple driving error.



"The impression I had was that it was a mistake," former triple world champion Stewart added.



"I think he accelerated too hard out of the corner, and there is no longer traction control," the Scot noted.



From Brazil, Massa on Wednesday insisted that his spin was caused by "different problems" that were "not linked to traction control", and denied that he is having trouble adjusting to life without electronic aids.



But another former triple world champion, Niki Lauda, told Sport Bild: "If it wasn't a technical defect, he will be under terrible pressure in Italy.



"From Bahrain onwards, he can not afford to make any more mistakes," he added.