The Cubs are set to sign ace lefty Jon Lester to a six-year, $155 million contract, during which he will win a minimum of 140 games and strike out an average of 180 batters a year.

“Those are just the baseline expectations,” said Cubs President Theo Epstein. “He could do much, much better than that. We’ll just have to wait and see.”

Epstein said he wasn’t a betting man, but predicted Lester would go 148-6 during his six years with the Cubs, striking out 1,100 batters while maintaining a 2.58 ERA.

Lester — a future five-time Cy Young and three-time World Series MVP was slightly less optimistic.

“Has any pitcher in the modern era won 23 games a year over a six-year span? I feel like that’s a lot,” said Lester, moments after inking his contract. “I’m good, but I’m not that good.”

Added Lester: “Maybe everyone should temper their expectations at least a little bit for now.”