The Belmont Stakes marks one of the biggest days on the racing calendar each year, but the third jewel of the Triple Crown isn’t the only star attraction. Belmont Park will this year host a whopping six Grade 1 (the highest level of competition) stakes races on Belmont Stakes day, June 9, plus additional stakes. Three of the "undercard" races are Breeders' Cup Challenge races offering the winner an expenses-paid berth to the year-end championships. Read on for the scoop on what each Grade 1 race means and why they’re so important.

Acorn Stakes

The Acorn is a race for 3-year-old fillies that was first run in 1931. Contested at a mile and carrying a $700,000 purse, the Acorn is often the next goal for fillies that run in the Kentucky Oaks a day prior to the Kentucky Derby. Over the years the Acorn has also been a part of the New York Filly Triple Tiara, a “triple crown” of races for 3-year-old fillies, and the race has been won by such greats as Inside Information, Sky Beauty, Open Mind, Davona Dale, Ruffian, and Gallorette. This year's field is expected to include Kentucky Oaks winner Monomoy Girl, last year's champion 2-year-old filly Caledonia Road, and multiple Grade 1 winner Moonshine Memories.

Belmont Stakes

American Pharoah winning 2015 Belmont Stakes. (Eclipse Sportswire)

This one is self-explanatory. This year’s Belmont Stakes marks the 150^th edition of the race that serves as the final jewel of the Triple Crown. Even for horses not named Justify, winning a historic, 1 ½-mile race with a $1.5 million purse is a nice feather in their cap, and colts who win the race are virtually guaranteed a chance at stud once their racing days are over. A field of 11 is expected for the race, including Preakness second- and third-place finishers Bravazo and Tenfold, plus Hofburg, Gronkowski, and more.

Longines Just a Game Stakes

The Longines Just a Game is a turf race that features some of the best female milers each year. The $700,000 race was first run in 1992 and was named for the 1980 champion turf female Just a Game. In its brief history the race has been won by such outstanding turf mares as Memories of Silver, Intercontinental, Ventura, Tapitsfly, Stephanie’s Kitten, and Tepin. This year's field is slated to include Cambodia, La Coronel, and Off Limits, among others.

Runhappy Metropolitan Handicap

The Runhappy Metropolitan Handicap is better known as the Met Mile, and it is one of the marquee races for older horses on the calendar each year. It’s been around since 1891 and the list of horses who have won it reads like a who’s who of the sport: Equipoise, Tom Fool, Native Dancer, Sword Dancer, Kelso, Carry Back, Buckpasser, Forego, Gulch, and Holy Bull, to name a few. This year’s field is competing for not only a $1 million purse but also an expenses-paid berth in the Breeders’ Cup Dirt Mile this fall at Santa Anita Park as part of the Breeders’ Cup Challenge “Win and You’re In” series. Awesome Slew, Bolt d'Oro, Good Samaritan, and Mind Your Biscuits are among the expected contenders this year.

Ogden Phipps Stakes

The historic Ogden Phipps is another Breeders’ Cup Challenge race, this one for fillies and mares at 1 1/16 miles. The winner will receive the lion’s share of a $750,000 purse and a berth into the Longines Breeders’ Cup Distaff in November. The race began as the Hempstead Handicap in 1961 and has a history of the nation’s best competitors — winners include Ta Wee, Personal Ensign, Sky Beauty, Serena’s Song, Ashado and Close Hatches. 2017 Kentucky Oaks winner Abel Tasman headlines this year's field which could also include Ivy Bell, Pacific Wind, and Unbridled Mo.

Woodford Reserve Manhattan Handicap

The Woodford Reserve Manhattan has been around as long as the Belmont Stakes, first run in 1867. The race is held at 1 ¼ miles on the turf, and with a $1 million purse the race is often targeted by top turf males. Named for the borough in New York, the Manhattan has been won by such storied racehorses as Preakness (for whom the Pimlico classic race is named), Stymie, Round Table, Sky Classic, Paradise Creek, and Gio Ponti. Beach Patrol, Hi Happy, and Sadler's Joy are among those expected for this year's edition.