Marquez is desperately looking to turn his season around, having struggled in the opening six races, recording just one victory and a single additional podium finish.
In an effort to find a solution for his under-performing Honda, Marquez tried out the 2014 chassis at a recent in-season test. While the Spaniard was not able to get as many laps under his belt as he would have liked due to inclement weather, he saw enough to convince him to try it out once more in Thursday's practice sessions.
The move paid off as he recorded the second-fastest time during Thursday's FP2 despite falling on his out-lap during FP1. As a result, he will use the 2014 chassis with recent upgrades this weekend.
"I used the 2014 chassis for all the sessions plus the new swingarm that I have used from Le Mans," he told reporters. "It looks like it is working well and also I have a good feeling with the bike but still in some points I think we are able to improve.
"We would like to make another [chassis] comparison here but here we thought it was not a good idea because always have the conditions and if tomorrow it rains then we lose time. We will try on some tests but here we will use only 2014. It is more the entry in the corner where I complain all year."
Marquez was at a loss of words to explain how he crashed in FP1, but seemed to narrow it down to the track being dirty or a cold tyre.
"It was really strange and I didn't understand," he said. "It was the first lap and maybe I was off the line and the track was dirty or maybe it was the cold tyre. In the end I went straight to the garage and it was ok.
"It was much slower because it was the first lap but it was strange and also scary and it was a wake-up."