The 2018 NCAA DI women's track and field championships were decided by a dramatic comeback and photo finish in the 4x400 relay that gave Southern California the exact points needed for the NCAA title.

This was no ordinary 4x400 relay. With championship implications, a watery track and a nearly costly error, Southern California's victory became an instant classic in the annals of college sports.

Let's break down how the improbable finish happened:

1. The Trojans had to win or go home

USC entered the race with 43 points. They were in third place, trailing Georgia, who had 52 points, and Stanford, who had 51 points. Neither the Bulldogs nor the Cardinal had a team in the 4x400, which left the Trojans hope. The only way that USC was winning the 2018 national championship was with a first-place finish and ten points from Kyra Constantine, Anna Cockrell, Deanna Hill, and Kendall Ellis.

That's just what Southern California did, winning by one point and the narrowest margin of victory since 2004. For the second straight year, Georgia watched its championship slip away in dramatic fashion after finishing as national runners-up to Oregon similarly in 2017 by 1.8 points.

RELATED: USC women, Georgia men capture 2018 DI track and field titles | Results

2. The runners dealt with unfavorable conditions

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As is seemingly customary in Oregon for the track and field championships, the rain fell for the better part of four days at the 2018 track and field championships. That final Saturday saw torrential downpours in chilly weather with sleet and hail even reported at moments of the day. Though the rains had subsided by this deciding final race, the track was still slick, making the fourth-fastest 4x400 time in Southern California school history perhaps the most memorable.

3. USC bobbled the handoff

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The Trojans actually began to make up some ground heading into the anchor leg. Deanna Hill moved into third place, but when she went to hand the baton to Ellis, there was a bobble and a minor collision, making Ellis' feat more remarkable. The contact led to a post-race protest, however after review, it was ruled incidental contact and the Trojans were champions.

4. The announcers were stunned

Dwight Stones and Jill Montgomery's call of the race help to make this dramatic finish that much more memorable. The emotional roller coaster everyone at Historic Hayward experienced is expressed in their voices to a tee, especially in the final meter of this instant-classic. Convinced the race was Purdue's to lose, they quickly changed their tune in the final 15 seconds of the dramatic finish.

3:09.5 Montgomery: “I just don’t know if Purdue is going to get caught.”

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3:11: Stones: “No, there’s no way unless they drop the baton. Purdue is going to win this, which we certainly didn’t see.”

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3:18.2 JM: “Here comes SC.”

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3:19: JM: “Oh my gosh”

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3:21: DS: “USC is not going to catch Purdue I don’t think.”

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3:21.9 DS: “Oh my goodness, oh my goodness, USC wins the women’s track final on the last meter of the 4x4.”

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5. The fans' reaction

Oregon, the "home team" at Historic Hayward Field in Eugene, had plenty of fans on hand. Despite watching their Ducks fall from second to third alongside Purdue fans in the improbable finish, fans rose to their feet, including a couple of Purdue fans in disbelief. Check out those with their cell phones out in complete awe of one of women's outdoor track and field's most memorable moments.

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Wayne Cavadi is in his third year covering all things Division II sports for NCAA.com. In the “offseason”, he covers the Atlanta Braves minor league system for FanRag Sports and SB Nation’s Minor League Ball. His work has appeared on Bleacher Report, MLB.com, AJC.com and FoxSports.com.