Top model Kate Upton has done the unthinkable and landed the prestigious Sports Illustrated Swimsuit cover two years in a row.

The curvy beauty is shown posing for the 50th anniversary issue topless on a boat in Antarctica, covered only by a white fur-lined parka and white bikini bottoms.

Sports Illustrated had hoped to announce Upton’s big coup on CBS’s “Late Show With David Letterman” on Monday. But after Page Six was sent a leaked copy of the cover yesterday, the magazine confirmed that Upton was indeed their cover star.

By clinching the 2013 honor — and the 50th anniversary issue — Upton solidifies her status as one of the world’s top models. It is the first time since 1988 that a model has won consecutive covers. Elle Macpherson was featured three years running, from 1986.

Last year, Upton made men swoon when she appeared on the SI swimsuit issue wearing the skimpiest of bikinis over her voluptuous curves.

The blond bombshell has since parlayed her SI cover fame into a successful high-fashion career, appearing in several issues of Vogue, modeling for photographer Terry Richardson and appearing in a Super Bowl ad for Mercedes-Benz during last week’s game.

Page Six reported last month that 22-year-old model and Swimsuit rookie Hannah Davis — the girlfriend of Yankee captain Derek Jeter — also had a strong chance to nab this year’s cover. Davis made a “rare, huge first impression” on editors, we’re told.

On the Upton cover, Davis also appears in a smaller image, with the caption, “Hannah Davis: The Dreamy Rookie.”

Other top models in the running were Julie Henderson, Miss Alabama 2012 Katherine Webb, Alyssa Miller and Nina Agdal. They’ll all appear on Letterman on Monday with Upton, and then are expected to travel to Las Vegas.

SI last night confirmed Kate’s cover on its Web site with the line,“You can’t hold back Kate Upton.”