As Yahoo (YHOO) prepares to report quarterly earnings — and perhaps a buyer of its core business — the former interim CEO said he's expecting a bruising for the internet pioneer.

"I think the prediction is pain," Ross Levinsohn, former interim Yahoo CEO, told CNBC's " Fast Money: Halftime Report " on Monday, quoting iconic fight film "Rocky III." He said he'd have a hard time seeing the core business going above a $5 billion bid.

"There's just an incredible amount of work to do," Levinsohn said.

It comes as Yahoo has faced shareholder pressure to sell its internet assets, as its shares in Alibaba (BABA) have soared in comparison.

"The core of it is still fantastic — great people, terrific brands," Levinsohn said. "But I think the focus of where they invested ... just has not paid off."

Yahoo is said to be whittling down final bidders for its core business as soon as today, although Levinsohn — who said he was involved in the bidding process through Bain Capital — said he doesn't expect an announcement for a couple of weeks, since it seems like some of the bidders needed more time.

He said he expects the company to trade in the $3.5 billion to $4 billion range — especially when the core business is valued dispassionately, outside of the drama and intrigue that has surrounded the company over the past decade.

As someone who has looked under the hood of the company and been with it from the beginning, it's "super hard to do," he said. Levinsohn said he understands why Yahoo's leadership did what it did, as far as buybacks, perks and acquisitions.

"The state is troubled, clearly," Levinsohn said. "We can look back over the past four years and see the strategy did not pay off."

It makes "a ton of sense" for both Verizon and AT&T to buy Yahoo, Levinsohn said, although he's partial to the combination of AOL's Tim Armstrong and the distribution on Verizon phones. A private equity play might also be needed for "deep cost-cutting" and a "sober" approach to the business, he said.

"You've got an asset that is troubled, that doesn't mean you can't turn it around," he said. Yahoo declined to comment Levinsohn's remarks.

Meanwhile, someone like Dan Gilbert, a wildcard bidder, is a "terrific operator," Levinsohn said.

But in any case, Yahoo needs to be cleaned up, he said — and that's not just CEO Marissa Mayer's fault, he said.

"If you're the CEO of a big, high-profile company, you take the good with the bad," he said.

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