Until Sunday, Sergio Garcia was considered the best golfer of his generation never to have won a major championship.

Suddenly, he's the only golfer who can win the Grand Slam this year.

Thanks to his breakthrough victory in the Masters, Garcia's odds of winning the U.S. Open at Erin Hills in June dropped from 40-1 to 20-1, according to Bovada.

But he will show up in the Kettle Moraine knowing precious little about Erin Hills, an 11-year-old public course playing host to Wisconsin's first-ever U.S. Open.

Other than golfers who competed in the 2011 U.S. Amateur (including Jordan Spieth) or the Erin Hills Intercollegiate hosted by Marquette University, almost none of the U.S. Open competitors will have seen the course.

Though Erin Hills is closed and will not open to the public until after the Open, John Morrissett, the competitions and marketing director, said championship qualifiers will be able to play practice rounds after mid-May.

Golfers will encounter some striking similarities to Augusta National, but some significant differences. Here they are:

5 SIMILARITIES

Back-nine drama: Augusta National has Amen Corner, perhaps the most famous stretch of holes in the world. The back nine also includes two reachable par-5s that produce everything from eagles to "others." The genius of the course design is that golfers have to weigh risk vs. reward on so many shots.

Erin Hills has a similar stretch of dramatic holes on its back nine. Depending on the wind and tee placements, No. 14 can be a reachable par-5 and No. 15 can be a drive-able par-4 (as it was during the final round of the U.S. Amateur). So there is the potential for back-to-back birdies before a difficult three-hole closing stretch.

Topography: On both courses, "topography plays a dominant role," Morrissett said. Augusta National mostly slopes from the clubhouse down to Amen Corner, while Erin Hills is more rolling, with ridges, mounds and valleys typical of the Kettle Moraine.

Around the greens: Golfers are sometimes uncomfortable with multiple shot choices around the greens because options can lead to indecision. At Augusta National, they might putt, hit bump-and-run shots with hybrids or use their lob wedge to hit high, soft-landing pitches.

The same will be true at Erin Hills. Typically, the golfer who misses a green at the U.S. Open automatically reaches for a wedge and chops out of deep rough. But the green surrounds are closely mown at Erin Hills, so you'll see some of the same shots you saw at Augusta.

The invisible hazard: Professional golfers have no problem with cold, rain, heat or humidity. It's wind that bothers them.

We saw how wind gusts of 25-30 mph affected scoring at the Masters last week. Even in relatively benign conditions on the weekend, a light breeze swirling through the pines affected shots.

"There's just enough of it to make a big difference," Steve Stricker said, "especially when the areas you have to hit (on the greens) are pretty small."

Erin Hills is regularly raked by wind and in June the direction and intensity can change from day to day. The course could play considerably different from Thursday to Sunday.

Fairway widths: Though the fairways at Augusta National are tighter since the course was "Tiger-proofed" in the late 1990s, they are still generous, which is one reason bombers have an advantage.

The landing areas at Erin Hills will be wider than typical U.S. Open fairways, so big hitters will have an edge — as long as their misses aren't too wild.

5 DIFFERENCES

History: Augusta National has more than 80 years of tradition and has been the scene of some of the most memorable moments in golf history.

Erin Hills opened in 2006 and is almost a complete unknown. The United States Golf Association gathered important data during the 2011 U.S. Amateur but executive director Mike Davis, who is in charge of course setup, will be feeling his way to a large extent.

Trees: The fairways at Augusta National are lined with loblolly pines, which influence strategy and often directly affect scoring.

At Erin Hills, there are only five specimen oaks on the interior of the course and they almost never affect play. A large oak once guarded the corner of the dogleg on the par-5 first hole, but it came down during a 2010 renovation.

Greens: Augusta National is famous for its enormous rolling, tilting, lightning-fast putting surfaces. Erin Hills has huge greens, too, and they will be shaved to achieve U.S. Open racecar speeds, but it's unlikely golfers will be worried about putting off them.

"There is nothing scary like (the ninth green) at Augusta, where you're worried about three-putting from 5 feet," Morrissett said.

Hazards: Golfers must deal with water hazards on Nos. 11, 12, 13, 15 and 16 at Augusta National. At Erin Hills, the only water that will come into play during the U.S. Open is the marsh that lines the left side of the fairway on No. 1.

The hazards at Erin Hills are the "sea of fescue" that will punish errant shots and more than 130 irregularly shaped bunkers, many of which are to be avoided at all costs.

Length: At 7,435 yards, Augusta National is long. But Erin Hills is in another league; it can be stretched to more than 7,800 yards and all four of its par-5s can play well over 600. It could wind up as the longest-ever U.S. Open venue.