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.
"But I am enjoying the moment. Today was a day in which I had more to lose than to gain, but I came out winning."
Reigning world champion Bagnaia scored back-to-back second places at Motegi, having cured the braking woes that plagued him in India.
A problem disengaging his pit limiter after his bike swap at the end of the opening lap dropped him down the order, but the factory Ducati rider rallied to get back into runner-up spot.
Bagnaia felt he could have caught Martin had the race run to its 24-lap distance, but agreed with the decision to red flag it when the conditions worsened.
"Yes, I could catch him, because Jorge did some first laps in which he pushed the tyre a lot, while I continued the same strategy as [Marc] Marquez, which was not to force the rear tyre too much," Bagnaia said.
"When it started to rain harder in the last laps, I saw that I was catching up with him.
"Unfortunately, the race ended at that moment, but it's okay, because afterwards it was too difficult [to continue]. We all want safety, so it was the right thing to do."
