Musk Concedes Claude Outshines Grok for Now, Pins Hopes on Version 5

For a rival AI model, Elon Musk had rare praise, calling Anthropic's Claude Opus 5.5 a masterpiece. He also conceded that xAI's upcoming Grok 4.8 will not match up.

Nevertheless, Musk maintains that Grok 5 could surpass Anthropic's leading model in a matter of months.

Elon Musk Discusses Claude AI

A reply from Musk came on Tuesday to an X user who had asked about the performance of Grok 4.8.

“Opus 5.5 is a masterpiece,” Musk wrote on X, adding that Grok 4.8 would be “not as good.”

Anthropic rolled out Opus 5.5 on September 22. The company says it is on par with its higher-end Fable 5.1 for most tasks.

On typical workloads, it also runs at 40% less cost than the prior Opus model. A 65.76% score was reported by Anthropic on Terminal-Bench 4.0.

OpenAI’s GPT-6 Astra, in contrast, notched 57.9% on the same benchmark.

No benchmark results for Grok 4.8 have been published by Musk. In the fiercely competitive AI sector, praise from a direct rival is highly unusual.

Can Grok 5 Really Surpass Claude Opus 5.5?

Musk is convinced it can. He stated that Grok 5 “should exceed Opus 5.5,” potentially within two or three months. No firm release date was provided, however.

Still, Musk has a track record of missing his own deadlines, so that timeline should be treated with caution by investors and users alike.

For the moment, xAI is putting the finishing touches on Grok 4.8. According to Musk, pretraining is done, although the model is still in the reinforcement learning stage.

A considerable amount of time was also spent cleaning up its supervised fine-tuning data. JAX and SGLang have been replaced by xAI with a new system written in C and C++.

Interestingly, Musk credited Starlink engineers with helping to build the training and inference stack. Borrowing SpaceX practices, the rewrite involves custom headers and precise time calculations, including leap seconds.

Grok 4.8 was described by Musk as “not yet incredible,” though he said its foundations are now solid.

A soft rollout to early users is expected by Musk later this week. No public response to his remarks has come from Anthropic.