Marc Marquez now believes his brother is his main rival for the 2025 MotoGP World Championship.

At the Argentine Grand Prix, Marc Marquez completed a Grand Slam (pole position, Sprint Race victory, Grand Prix victory) for the second time this season.

The runner-up to Marc Marquez throughout the weekend was once again his little brother Alex Marquez. The younger Marquez brother qualified in second and finished the Sprint Race and Grand Prix in second.

However, Alex did not make life easy for Marc and the eight-time World Champion has labelled his brother as his 'main opponent' for the 2025 title.

"Not always. When you pass 20 years old, 22, then it’s equal," Marquez stated after being asked if he goes easy on his little brother.

"But Alex today I’m very impressed about his riding style. He was super smooth.

"And I know when he is super convinced he is able to win a world championship, like he did in Moto3, in Moto2.

"So, at the end, he is the main opponent for the championship."

Marc Marquez admits he nearly settled for second:

At Turn One on the opening lap, Marc Marquez shot into the lead until he ran wide at the same corner on Lap Four. This mistake cost Marquez the lead and allowed Alex to slip through into the lead.

It was then not until Lap 21 that the older Marquez brother was able to regain the lead. Marc even admitted that he had considered admitting defeat to Alex.

"Today I’m impressed about my brother, about Alex," he added.

"In one part of the race I was thinking to finish second because he was riding super smooth, super good, always keeping the corner speed.

"I mean his tyre was not smoking. I said ‘ok, this guy today has another level’.

"Then in the end I survived. I took a risk, as you saw, I took a lot of risks - maybe too much in some points of the race.

"But happy to go out with 37 points again and continue with a very good atmosphere inside the garage, because the Ducati Lenovo team did an amazing job. But also inside the family."