The rivalry between Sam Altman and Elon Musk is entering its Apprentice era. Both men have the ambition to redefine how the modern world works—and both are jockeying for President Donald Trump’s blessing to accelerate their plans.

The relationship between Elon Musk and Sam Altman progressed from an initial friendship to a bitter rivalry. Here's why.

Sam Altman is leaving no room for doubt about his views on an Elon Musk-led bid to take control of OpenAI. In a letter to OpenAI staff Monday, the CEO put the words “bid” and “deal” in scare quotes and said the startup’s board has no interest in the offer.