The 2019 Circuit of the Americas winner made a lightning start from seventh on the grid to run fourth at the first corner, before scything into third later on the opening lap.
But his charge for the podium didn’t last long as he quickly slid back, eventually finishing 11.098 seconds behind race winner Marc Marquez.
Rins says he was battling traction issues all race, which meant he “couldn’t fight”, and is at a loss as to explain why he suffered with this problem.
“I think today was a very, very difficult race for me,” Rins said after Sunday’s race.
“I struggled a lot because exiting from the corners, we were losing a lot of time.
“I don’t know if it was for the rear traction, the aerodynamic package or what, but I couldn’t fight.
“I couldn’t hold the overtakes, at least the first metres in the straight.
“Then on the fast corners we were able to ride quite well, but we were losing a lot exiting from the slow corners.
Alex Rins, Team Suzuki MotoGP
Photo by: Gold and Goose / Motorsport Images
“We were so close to racing with the hard front and medium rear, in the end we saw that mostly all the riders were using the soft rear.
“So, to go with the same guns, we used the soft rear.
“[The bike] was not so bad [over the bumps].
“I was feeling a lot the bumps, but I was trying to survive. Was bumps for everybody. Because of the issues on traction and for the bumps [I was trying to survive].”
Team-mate Joan Mir had similar traction issues in Sunday’s race and took the chequered flag in seventh, though was later demoted to eighth for a final-lap collision with Ducati’s Jack Miller.
It was a penalty Mir later said he “didn’t respect” as he says he was forced into the contact because of Miller’s “strange” lines in the corners.
Regardless, it was a result that ultimately officially ended Mir’s title defence, with the Suzuki rider now 78 points off championship leader Fabio Quartararo with just 75 points left up for grabs in 2021.