The nine-time World Champion clocked finished the day in fourth place in the standings, with a fastest lap of 1m 55.581s some 0.674s off the pace set by Ducati's Andrea Dovizioso.
“It was a difficult day for me, because we tried to work a lot on the setting of the bike to improve and to be faster, but we didn’t get the improvement we expected," explained the Italian.
However, Rossi was buoyed slightly by an increase in performance late in the day.
"I was in a difficult situation, but fortunately in the last hour we modified something. We did a step back and went a different way. The last part of the test was good, because I was fast with both the hard and the soft tyre and I was able to improve my position so I’m in the top five, but especially I was able to improve my pace and stay in the 1’55’s so at the end it was not so bad.
"We have to continue working for tomorrow and try to fix as much as possible for the weekend of the race. We have some other things to try; some different parts, settings and we have to decide on the tyres. It looks like today was hard work, a lot of laps, a lot of effort, but at the end it was a good day. We did good work and we found something good at the end.”
Yamaha team director Massimo Meregalli expressed optimism that the team are heading in the right direction.
"We still have some work to do to find half a second to close the gap but we are making progress in the right direction and have both riders further up the timesheet’s. We are confident that for tomorrow’s session when there is more rubber on the tarmac we will be able to close the gap even further," he said.