Ferrari has decided against using Felipe Massa's free engine 'joker' for this weekend's Belgian grand prix.

After winning in Valencia, the Brazilian driver said the Italian team should consider the option, given Ferrari's recent engine reliability problems.

The rules in 2008 allow each driver to make one unscheduled engine change without incurring the ordinary penalty.

But with his Budapest failure and teammate Kimi Raikkonen's Valencia problem apparently traced to a bad batch of conrods, Ferrari figures are now feeling more confident about their engine.

"We believe that we understand the problem we had, so I will not be changing my engine," said 27-year-old Massa, who began a new two-race cycle with his current engine in Spain two weeks ago.

"My engine of Valencia had a different conrod installation and so we are much more confident to be able to not repeat the problem," he explained in the Spa-Francorchamps paddock.

Source: GMM