Alonso (left) and Rossi (right) are reigning world champions

The Renault driver, who is fine-tuning the defence of his Formula One world crown, has been quick to strike the first psychological blow of 2006.

"I'm glad because that means they have lost valuable time preparing the cars for the show they put on," he said.

"Let him come and drive. It's good because there will be more attention."

Until we see him race we won't know his true potential, but it will be very difficult for him Alonso on Rossi

Yamaha rider Rossi, 27, has won motorcycling's top category for the last five years and has been linked with a move from two wheels to four after several tests with Ferrari.

After a number of private tests, he recently had his first test along with other F1 drivers, and seven-times world champion Michael Schumacher said he thought Rossi had the ability to compete in F1.

But Alonso seemed unimpressed, saying testing was not the same as competitive driving.

"Until we see him race we won't know his true potential, but it will be very difficult for him," he said.

"He can do well, because he will be driving a Ferrari, and can finish in the top five. But, from that to winning a Championship or races you need more.