Editor's note: This story was originally written prior to UFC 213. It has been updated to reflect the new date of this fight at UFC 215. With the cancellation of Demetrious Johnson vs. Ray Borg on Thursday night, this fight will now be the main event of UFC 215.

Amanda Nunes (14-4) defends her UFC women's bantamweight belt against Valentina Shevchenko (14-2) in UFC 215's main event on Saturday. This fight was originally scheduled to be UFC 213's main event in July, but Nunes pulled out, citing illness.

In advance of their rebooked rematch this weekend in Edmonton -- they first met in the UFC 196 pay-per-view opener, a unanimous-decision win for Nunes -- I watched each fighter's previous three bouts to gather points of emphasis.

Round 1: UFC 196

Nunes is a notoriously fast starter, with six first-round finishes in seven UFC wins. Her victory over Shevchenko in March 2016 is the lone exception.

As has been the case for Shevchenko since her Muay Thai days, "Bullet" spent the opening five minutes gauging range, allowing Nunes to reveal her hand a little bit, as far as her strategy goes. Nunes relied on low kicks to take a slow first round.

The fight turned one minute into the second round with a clever trip by Shevchenko, although Nunes quickly regained her footing. "The Lioness" instantly returned the favor, landing in Shevchenko's half-guard. Nunes used a heavy top game to open up her opponent, nearly securing a rear-naked choke finish. Two judges scored the lopsided round 10-8.

The third round revealed Shevchenko's significant cardio advantage. The Kyrgyz punished Nunes' half-hearted takedown attempt and landed in side control, a takedown in her only attempt. Though the Brazilian ultimately returned to her feet, Shevchenko was visibly more effective with her striking, claiming her only round.

The cards were read in Nunes' favor -- to no one's surprise -- 29-28, 29-27, 29-27, setting her up with a title shot against soon-to-be champion Miesha Tate.

Amanda Nunes' jabs were the key to her quick victory over Ronda Rousey, left, at UFC 207. AP Photo/John Locher

The champion

All cards on the table: I've been bullish on Nunes for some time. But there was far less to be learned in knockouts of then-champion Tate and then-legend Ronda Rousey than there was to see in Nunes' decision win over Shevchenko.

Neither title fight lasted four minutes, as Nunes' long, snappy jabs were too much for both of her opponents. The striking defense for Tate and Rousey could only be described as poor. As the challenger at UFC 200, Nunes stunned Tate with repeated jabs and crosses. Nunes calmly took her downed opponent's back, sunk in both hooks and tapped Tate with a rear-naked choke. Nunes finished with a 40-3 striking advantage to capture the women's bantamweight belt.

In Rousey's return fight at UFC 207, Nunes used simple, precise one-two combos again to dominate the once-untouchable champion. From the stare-down until the knockout finish, Nunes' confidence and composure never wavered. She decimated Rousey in 48 seconds, landing 27 strikes while absorbing just seven.

Valentina Shevchenko has succeeded in each of her past two fights by successfully implementing a similar plan to the one she took into her first fight with Amanda Nunes. Kamil Krzaczynski/USA TODAY Sports

The challenger

Shevchenko is known, understandably, for a world-class combination of Muay Thai, kickboxing and taekwondo. But her vastly underrated grappling is what secured Shevchenko this title shot.

When she faced former champ Holly Holm four months after losing to Nunes, it was another deliberately slow start, as Shevchenko used early kicks to find her range. She showed comfort in allowing Holm to lead, and countered with compact right hooks, repeatedly landing against one of the UFC's most decorated strikers. It didn't take long for Shevchenko to become the second fighter to take down "The Preacher's Daughter" -- and she did it three times. Bullet remained calm, continuing to connect with precision as Holm's desperation showed in the final moments.

Against Julianna Pena in January, Shevchenko twice timed thrown knees in the clinch and felled "The Venezuelan Vixen" with slick trips. She used heavy top position to win the opening round. Whether her back was against the cage or the mat, as it was after an eventual takedown by Pena, Shevchenko's calmness prevented overexposure. In full guard, Shevchenko worked her legs high enough to flip her left across Pena's face and force a tap with a belly-down armbar. It's Shevchenko's only finish in the UFC, and first submission win in more than a decade.

Vegas oddsmakers think the rematch between Amanda Nunes, left, and Valentina Shevchenko is too close to call, with the small adjustments each fighter is sure to make likely to serve as the deciding factor. Josh Hedges/Getty Images

What to watch

Nunes has been on even odds, or the outright underdog, in six of her past seven bouts, and she's 6-1 in those fights.

That's where the champion finds herself again; this rebooked title defense has Shevchenko the slight, minus-120 favorite, if not a pick 'em.

What makes the fight so difficult to predict is the obvious adjustment for each since their first meeting.

Shevchenko can't be content to yield the opening exchanges. That was the only competitive portion at UFC 196, and she has to start faster in what projects to be a close fight.

Nunes' cardio has to hold up better. If the first bout had been a five-rounder, conventional wisdom is that Shevchenko would've either finished the gassed Brazilian or continued to pull away to level points in the championship rounds.

That may mean conserving energy, unless there's an opening for an early finish against the durable Shevchenko, of course.

These two fighters are among the most dangerous strikers in the division with vastly different, but equally excellent, footwork. Tape suggests footwork in the clinch is where the title gets decided. Nunes has a brown belt in judo; Shevchenko holds a black belt. Both showcased deft trips last March, as damage inflicted in top position made all the difference.

I expect that to be the case again at Rogers Place, with both 29-year-old participants deeper into their primes. That offers the potential for a technical classic.