The Spaniard, riding just six weeks after suffering a broken leg that wrecked his pre-season, was behind both Jorge Lorenzo and Stefan Bradl when they crashed while leading, on laps one and eight respectively.
Marquez, the only rider to select Bridgestone's harder rear compound, says he modified his style accordingly, which in turn allowed him to push harder and prevail in his late battle with Valentino Rossi.
"So many riders crashed, you could lose the front end so quickly," he said.
"I chose the harder rear and was a bit worried in the beginning; honestly I lost confidence.
"I had some problems with the front of my bike in the beginning, so I just tried to stay behind Bradl and then attack a bit more in the final 10 laps.
"I think the first laps were key. If I pushed more, maybe I would have crashed."
Marquez said his victory was all the sweeter following the dramatic late duel with Rossi, adding: "it was so great, I enjoyed it a lot.
"The last lap I pushed 100 per cent; the lap before we passed each other three or four times.
"Last year we had our first battle and he won it, this year was the second. I hope we have more in the future.
"It's a great start to the championship, not only for the result and the 25 points but also for the show. I think it was so nice for the fans."
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- Stefan Bradl
- Valentino Rossi
- Jorge Lorenzo