Louisville, Ky. — After five relatively easy victories, Monomoy Girl proved it could also handle challenges in the Kentucky Oaks.

The filly first overcame an outside post start before gutting out a close win to maintain its hot start.

Monomoy Girl took charge near the far turn, and the filly outdueled Wonder Gadot down the stretch to win the $1-million Kentucky Oaks by half-a-length on Friday at Churchill Downs.

A race expected to match the top two 3-year-old fillies in No. 2 Monomoy Girl and points leader Midnight Bisou, the morning-line favorites, soon became Monomoy Girl’s to lose. The chestnut filly charged from the outside No. 14 post into contention and the lead and held ground in a thrilling side-by-side stretch battle with Wonder Gadot before Monomoy Girl kept the small edge to the wire.

Monomoy Girl entered the Oaks with five wins in six starts by a combined margin of 20½ lengths. Its latest triumph was much tighter, which made the signature win before 113,510 all the more satisfying.

“It’s great, you know,” jockey Florent Geroux said. “She was in a war, she had only one try.

“This filly has been very special for us, known for a long time. We’ve been pointing to this race since November, to get here in good shape and winning. She was just outstanding.”

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The filly’s win first had to be confirmed by racing stewards.

Wonder Gadot’s jockey, John Velazquez, filed a foul claim against Monomoy Girl for a bump down the stretch. The claim was quickly dismissed, giving trainer Brad Cox a defining hometown win in the 144th running of the Kentucky Oaks.

“Obviously, the biggest victory in my career,” said Cox, who had two other entrants in Sassy Sienna (sixth) and Kelly’s Humor (eighth).

Monomoy Girl covered 1 1/8 mile in 1:49.13 and paid $7.20, $4.60 and $3.60.

Wonder Gadot returned $14 and $7.20. Midnight Bisou finished third, paying $3.20 while having its three-race winning streak snapped.

The biggest surprise was that Wonder Gadot, initially a 20-1 shot, gave Monomoy Girl its biggest challenge instead of Midnight Bisou. The California-based filly entered with three wins by 10¼ combined lengths, fueling expectations of a two-horse race.

Midnight Bisou came on late, but behind the two other fillies that battled hard in the dirt.

Monomoy Girl’s main question was how it would handle an outside post and stake its place against 19 other horses fighting for position. Cox, who grew up blocks from Churchill Downs, wasn’t fazed. He believed his horse had the speed to get into contention along with the patience to navigate traffic.

Monomoy Girl ultimately had no trouble running outside the crowd before gaining position near the rail and holding on. A brief wait followed before stewards upheld the finish, which sparked a celebration among Geroux, Cox and Monomoy Girl’s owners.

Velazquez felt justified in claiming foul.

“At least I have to take a chance on it,” he said. “I mean, I’m fighting the whole way around and all of a sudden the last sixteenth of a mile she goes back to her left lead because she got bumped.”

Monomoy Girl’s Oaks win came hours after last year’s winner, Abel Tasman, was beaten in its return to Churchill Downs as a 4-year-old.

The filly finished fourth among six horses in the Grade 1 La Troienne Stakes, in which Salty beat Farrell by a head.

Kentucky Derby winner Always Dreaming also had a tough day. The colt and race favorite in the Grade 2 Alysheba Stakes got out fast and battled eventual winner Backyard Heaven through the final turn but faded to a fifth-place finish.