Jahmai Mashack understood he had a tall task — in every sense.

Mashack was an Etiwanda High School junior preparing to face Rancho Christian and its 6-foot-11 All-American Evan Mobley. The future Tennessee basketball guard was part of an undersized Etiwanda team playing to keep its season going in the California state playoffs.

The 6-4 Mashack accepted he was going to guard Mobley. He needed an edge, something to make up for a 7-inch difference and something to defeat Mobley after losing the year prior.

He found it in solitude, watching all the film on Mobley he could to garner any potential advantage. Mobley, the future No. 3 pick in the 2021 NBA Draft, had seven points and Etiwanda advanced.

Mashack’s approach to basketball changed then. He was hooked on preparation in a new way, a manner that makes him who he is on the court. Four years later, it is as much compulsion as it is habit — and it’s why he’s a defensive ace for the Vols.

"For me, it is like I have to do it,” Mashack said. “Even more if it is a big game, I have to do it. I have to get that information to give me a slight edge. This is something I am known for. I am known for defense.”

How Jahmai Mashack studies film of Tennessee basketball opponents

Mashack planted himself next to Zakai Zeigler and Jonas Aidoo after a February practice. The three juniors playfully talked for a while. Mashack got up and shot some free throws before exiting Thompson-Boling Arena at Food City Center to go and shoot at Pratt Pavilion.

His physical work complete, he returned to the arena in a new spot to study film. These quiet moments are when Mashack sharpens his preparation, adding as many tools to his belt as possible.

“I want to go above and beyond,” Mashack said.

Tennessee is playing LSU the following day. Mashack is focused on LSU’s top guards Jordan Wright and Jalen Cook, who averaged a combined 30 points per game at the time.

He gets out his iPhone to watch clips of the pair, which director of video and analytics Luke Schapker uploads to Huddle before each game. He receives a breakdown of each player and 50 clips of each, which he can — and does — watch at his leisure.

He starts with Wright. He is familiar with the Vanderbilt transfer from prior years. Wright is smart and the film shows it. Mashack only needs one clip to identify why Wright will be a challenging guard: He always makes the right play.

That’s Wright’s thing. He isn’t likely to score 10 points in a spurt, but sprinkles points when he sees the moment. He is comfortable with contact and isn’t bothered by being near the rim. Mashack doesn’t think he will be able to speed Wright up. Wright attacks close outs well and correctly, which means Mashack plans to close out hard but too closely so he is in position to retreat if Wright drives.

“Wright is more a threat because he doesn’t force the issue,” Mashack said. “As a defender, without even realizing it, you are kind of forgetting about him a little bit and that is when he hits you.”

Cook, who did not play against UT due to injury, is the opposite. He hunts shots more than Wright. On the first clip, Mashack sees Cook use four hesitation dribbles at various moments. Each one is trying to set up a shot. That is Cook’s go-to, throw move after move until he sees an opening to shoot. Mashack plans to guard Cook closer than Wright and rely on UT’s big men for help on screens.

The key with Cook is to say in front of him and not to bite on the hesitation moves, Mashack says. He needs to make Cook feel his presence.

Wright and Cook both require relentless attention. But where Wright demands it so you don’t slack, Cook calls for it because he is always positioned to shoot. Cook might airball a 3-pointer then shoot again.

“Those are tough guys to guard because you think okay I played good defense maybe I can relax, but you can’t,” Mashack said. "He will come down and shoot again.”

Why preparation is essential for Jahmai Mashack

Mashack is a physically gifted defender. That part of his game cannot be neglected in the conversation about his obsessive preparation. He has a sturdy build and is not easily moved. He has quick hands, opens his hips well and his feet don’t stop moving.

That is half of what Mashack says makes him good defensively. The other half is film.

“That is a big 50%,” Mashack said. "I am not half the defender I am without watching a lot of the film that I do.”

Mashack has refined the process that started his junior year at Etiwanda. He has more tools at his disposal at Tennessee. He learns in team film sessions, which show how players play off each other. He studies the numbers from scouting reports as well. He marries that data with his solo film study, which often comes late at night with his iPad in his room.

It is in those sessions that Mashack finds out how a player moves. He identifies if a player is a catch-fire scorer or a steady threat. He dissects an opponent’s skill set to discern their spots on the floor, how they play based on the score, and how they respond to pressure. He picks apart go-to moves and preferences.

A player is always going to lean into doing what they naturally do on the court, especially in pressure moments.

It’s all an information game to Mashack. He is gathering intel before a game and during it. He wants to see an emotional response that shows a player is fearful or tired, anything that he can use.

“People are going to operate out of their feelings,” Mashack said. “If your feelings are into the game and you are emotional, that can come off in your play.”

Mashack has seen it happen often at Tennessee. He can explain the success the Vols had in defending some top talents such as Illinois’ Terrence Shannon Jr. this season and Alabama’s Brandon Miller, the second pick in the 2023 NBA Draft, last season.

That's what he saw against Mobley four years ago. He knew enough from film about Mobley to handle him. Mashack could bump him enough to bother his timing. He knew how to keep Mobley away from where he liked to catch the ball and how to make him pass. He dared Mobley to shoot midrange jumpers.

“I remember all of it,” Mashack said.

That, too, is one of Mashack’s many gifts.

Mike Wilson covers University of Tennessee athletics. Email him at michael.wilson@knoxnews.com and follow him on Twitter @ByMikeWilson. If you enjoy Mike’s coverage, consider a digital subscription that will allow you access to all of it

This article originally appeared on Knoxville News Sentinel: How Jahmai Mashack prepares to be Tennessee basketball defensive ace