Musk called Claude Opus 5.5 a masterpiece and admitted that Grok 4.8 cannot compete

Elon Musk responded to user Dimdv's question on X, stating that the upcoming Grok 4.8 is "not good enough" compared to Anthropic's Claude Opus 5.5, and called "Opus 5.5 a masterpiece." He added that the next-generation model Grok 5 is expected to surpass Opus 5.5 in two to three months, but did not provide a comparative score or a specific release date.

Musk also disclosed the progress of Grok 4.8: the model has completed pre-training and is still undergoing reinforcement learning, with the team spending significant time cleaning the supervised fine-tuning data. He mentioned that xAI has abandoned JAX and SGLang, opting for a reasoning and reinforcement learning system rewritten in C and C++, and stated that Starlink engineers are involved in building the relevant training and reasoning tech stack. Grok 4.8 is expected to be launched this week for a limited number of Bot users.

Anthropic released Opus 5.5 on September 22, achieving performance close to its high-end model Fable 5.1 on most tasks, with operating costs under typical workloads being 40% lower than the previous generation Opus. In the Terminal-Bench 4 test, Anthropic reported that Opus 5.5 scored 66.4%, while OpenAI's GPT-6 Astra scored 57.9%.