Elon Musk and Mark Zuckerberg were grumbling about each other behind closed doors long before talk of a potential cage fight, report says

• Before the cage match offer, Elon Musk and Mark Zuckerberg privately grumbled about each other, WSJ reported.

• Zuckerberg has reportedly been jealous of Musk's recognition as a tech pioneer.

• Musk has sulked over how quickly Zuckerberg became wealthy due to software, WSJ reported.

Tensions between Elon Musk and Mark Zuckerberg appear to have been simmering for quite some time — long before the two indicated they might be ready to settle their differences in a cage match.

The two men have grumbled about each other publicly and to associates for several years, The Wall Street Journal reported on Thursday.

Sources who had heard each man's gripes told the publication that the Meta CEO had yearned for the public recognition Musk has garnered over the years as a tech pioneer. The Tesla CEO was named as Time's Person of the Year in 2021 and has received wide recognition for running five different companies, including Tesla and SpaceX. Zuckerberg has also won Time's Person of the Year — but that was back in 2010, and he has become much less popular in recent years, taking hits in front of Congress and over Facebook scandals.

In 2017, Bloomberg reported that Zuckerberg was "incredulous" after a Facebook poll lumped him in with Bill Gates as a "former innovator" instead of labeling him as a "current innovator" with the likes of Musk and Jeff Bezos.

Meanwhile, Musk has sulked over the fact that the Facebook cofounder was so quick to profit off his software startup while the Tesla CEO focused on building physical products like electric cars and spaceships, people familiar with his comments told the Journal. Zuckerberg became the world's youngest self-made billionaire on Forbes' list of billionaires in 2008 at the age of 23. He took Facebook public five years later. It was one of the biggest initial public offerings in the history of tech. In contrast, Musk has said that there were points that both Tesla and SpaceX were on the brink of bankruptcy. He made Forbes' list of billionaires in 2012, at the age of 41.