The Ducati rider was in control of the race, two seconds clear of his teammate Francesco Bagnaia.
On Lap 9, Marquez made the critical error and slid out of contention to give ‘Pecco’ the win.
The Spaniard returned to the race but had too much damage to continue and eventually retired.
Speaking post-race, the six-time premier class winner said he cut the corner too much.
Although he didn’t explicitly cite it, the circuit was left wet in parts by rain in the lead-up to the race.
“In the easiest moment of the race that I was trying to control the distance I cut a bit too much the kerb at Turn 5 and I lost the front,” said Marquez.
“It was completely my mistake. Sorry for the team, I can say only this.
“The kerb, I already cut some corner some laps before, just I cut too much,” he added.
“I was too optimistic a bit. I was fully concentrated, it was not with that extra confidence, I was just riding, taking care for the hard braking corners where you make mistakes, but the rest of the track I feel super safe.
“I cut too much the course and there was a mistake, I lose 25 points, but we need to keep going on the same way, keep the same speed because I feel fast everywhere.”
MARC MARQUEZ HAS CRASHED OUT OF THE LEAD 😱😱😱
📺 Watch the #AmericasGP on ch. 506 or via @kayosports https://t.co/rXET2U5XYU#MotoGP #MM93 pic.twitter.com/d3LDS08Uw0
— Fox Motorsport (@Fox_Motorsport) March 30, 2025
Marquez to that point had been almost infallible.
Before the grand prix, the 32-year-old had taken all three pole positions and the Sprint wins.
His crash dropped him from the lead of the championship and put him one point behind brother Alex.
“Positive for us, because always I try to find the positive, is we are equal in the championship, one point behind Alex – so we restart a new championship,” Marquez joked.
“Tomorrow is a new week, we will have a good atmosphere in the family in the training because we are first and second in the championship and still we have that margin that we use in the worst way because we used it in an easy race.
“But at the moment we are still at the head of the championship.”
Ducati general manager Luigi Dall’Igna had mixed emotions.
“Today’s win was a great one for Pecco,” he said.
“For Marc, on the other hand, a missed opportunity: he was leading, it’s true, but the good and bad of MotoGP is that you never know.
“In any case, it was a very positive weekend for Ducati, with the win in both races and with four Desmosedici GP machines in the top four.
“We have one really happy side of the garage, and the other not as much, but this is racing and it’s nothing new for us.”
MotoGP returns on April 14 for the Qatar Motorcycle Grand Prix at Lusail.
