The former Honda rider's 1min 32.3secs was just 0.1secs behind his team-mate's best (set on day two) and a mere 0.2secs from Alstare Suzuki's
Yukio Kagayama, who led the field following Bayliss' day three fall.
"Overall, I'm happy with this week's test results," said the Italian. "I had a fall on Tuesday but I'm fine now, although I was pretty tired after we finished the long-runs. Basically everything has gone well, my times have not been bad and I was especially happy with the second fastest time that I set this morning. We have really clocked up a lot of miles on the track this week!
"We are still working towards the right set-up and although there's still work to be done, we're definitely on the right track. There are still two tests to come of course so let's say that we, and me especially, will continue to improve over the next few weeks," he added.
Kagayama's team-mate
Fonsi Nieto and Sterilgarda Ducati rider
Ruben Xaus joined Fabrizio in setting a best lap time of 1min 32.3secs.