One way people get under Donald Trump’s skin is to question his wealth. Trump who claims to be worth $10 billion (Forbes estimates it to be $4.5 billion), has been under scrutiny because despite his boasting, he hasn’t been very transparent with his wealth. He refuses to release tax returns that would give a better indication of how wealthy he is, but is using the excuse he’s under an audit for not releasing them.

Mark Cuban, the billionaire owner of the Dallas Mavericks likely knows this is a sore point with Trump and whether he did it out of amusement to troll Donald or if he was just making an observation, there is no doubt this will likely bring about some kind of response from the presumptive GOP nominee.

During the interview with ABC’s Bernie and Sid, Cuban said Trump was good at putting his name on buildings. Cuban said, “He’s good at that. Whether or not that’s made him a billionaire, I don’t know. He’s not transparent enough for us to actually know.”

He also said that while Trump is good at real estate, he’s “horrible” at other aspects of business. Cuban took particular aim at Trump attaching his name to almost anything:

Cuban went on to say that just putting your name on steaks, playing cards and water bottles is “not gonna make big bucks, no matter what.”

“It’s not like Trump Steaks were gonna make him $100 million,” he said. “It’s not like it was gonna make him $5 million. And you know, I asked him, ‘What the hell are you doing? Are you that desperate for money?’ Seriously,” adding Trump couldn’t say no if someone was going to write him a check.

Then came the part Trump is sure to hate:

Cuban also asserted that he was wealthier than Trump. “It’s not even close,” he said.

The politically minded entrepreneur clarified — “before all the Trumpians jump on me on who has more money” — that the reason he knows about Trump’s finances is because, when FEC reports are filed, all cash, bonds and liquid securities have to be listed.

“So we know without any question that, as of May 27, Donald doesn’t have more than $165 million in cash and securities and bonds,” Cuban said.

“And trust me, I’ve got a lot more than that in cash, securities, and bonds,” he continued. “And so, you know, I’m willing to bet dimes against dollars that that’s pretty much what he’s got.”

Ouch.

And Mark? The Trumpians are going to jump all over you. Believe me. Believe me.