AI: Elon Musk Praises Claude Opus 5.5 and Admits Grok 4.8 Trails

Elon Musk does not often give compliments to his competitors. Yet, on November 10 on X, the head of xAI acknowledged that Grok 4.8 remained inferior to Claude Opus 5.5, which he even called a “masterpiece.” He is now betting on Grok 5 to regain the advantage, with a target set at two or three months.

Musk acknowledges Anthropic’s superiority without hesitation

Anthropic is preparing its IPO, but the company can also be pleased with another compliment. On November 10 at 10:22 UTC, Elon Musk responded to an X user who asked him to compare Grok 4.8 to Claude Opus 5.5.

His reply was candid: “Not as good. Opus 5.5 is a masterpiece. But Grok 5 should surpass Opus 5.5, and that may happen in two or three months, with continued acceleration thereafter.“

Difficult to be more direct. The head of xAI acknowledges his model’s delay while promising a much more ambitious next generation.

The two models are not yet in the same category. Grok 4.8 continues its development, while Opus 5.5 has been available for several weeks. Meanwhile, Anthropic highlights its performance in agentic programming, with an announced cost 40% lower than Opus 5.

Grok 4.8, the final adjustments before launch

Musk also provided some details on the progress of Grok 4.8. Its pre-training is complete, but xAI still continues reinforcement learning. This step allows refining the model’s responses through a reward system. The team also reviewed the supervised data to improve its ability to follow instructions.

Another important change: xAI abandoned JAX and SGLang in favor of an infrastructure developed mainly in C and C++. The company seeks to better control the performance of its training and inference systems.

This technical choice sparked reactions from developers. When one of them launched “C wins again,” Musk clarified that it was “C with a bit of C++.” A nuance that clearly matters a lot behind the scenes at xAI.

However, this approach implies more internal maintenance. The abandoned tools benefit from well-established communities and ecosystems. Musk did not provide any figures to measure expected performance gains. He simply praised the work of Starlink engineers, involved in developing this infrastructure.

Grok 5 will already have to run after new competition

The schedule announced by Musk has a small problem: Anthropic does not intend to wait for xAI to catch up.

On November 9, the company unveiled Claude Fable 5.2 and Claude Mythos 5.2, presented as its most efficient models, especially in programming, finance, and science.

In other words, Grok 4.8 will still need to improve to compete with Opus 5.5, while Grok 5 will probably have to face a generation already newer from its competitor.

The financial context adds another dimension to this rivalry. Anthropic filed its IPO application on October 26 and launched its investor tour on November 10. The race for AI and capital is accelerating on both fronts.

For Musk, the next milestone will be Grok 5. The question remains whether xAI will meet its deadlines. In the artificial intelligence sector, two or three months can be enough to completely change the rankings.