The Pramac Ducati rider completed his second sprint/grand prix double in three rounds at Motegi last weekend to cut Francesco Bagnaia's championship lead down to three points.
Martin, who also qualified on pole, recovered from an early mistake after emerging from pitlane on his wet bike as the rain intensified as the leading stopper to win by 1.4s when the grand prix was red-flagged on lap 13 of 24.
Chased by Bagnaia in the latter stages of the grand prix, Martin insists his thoughts were not on the championship as he gunned for his third Sunday win of the season.
"I was committed to getting a good result today, when it started to rain I got behind Pecco to understand if he would stop or not [to change bikes]," Martin began.
"We stopped together and I started very fast, I was able to understand the conditions and I was able to get ahead.
"In the end it was very difficult and dangerous to continue."
He added: "I had to try to win. I wasn't going to my limit, because in water if you look for it you fall. I was very focused on winning.
"There is a lot of championship left, but if I had thought about the championship I would not have won, and with the slick tyres I would have held back more.
Source: Autosport