COSTA MESA, Calif. -- Los Angeles Chargers edge rusher Uchenna Nwosu is in a heated battle on the practice field. He arrives early, stays late and is working as hard and smart as he can. The player he's battling, Kyler Fackrell, is doing the same.

Who wins the starting spot will be settled either by Sept. 12, when the Chargers go on the road to face the Washington Football Team (1 p.m. ET, CBS). Or before.

It's not a position neither Nwosu nor Fackrell find comfortable. Both will see considerable playing time, but who the heck starts?

Nwosu was a second-round draft pick out of USC in 2019. He had 4.5 sacks and 33 tackles in a part-time role last season. Fackrell is in his sixth season in the NFL, after playing for the Green Bay Packers and the New York Giants. He was drafted by the Packers in the third round in 2016 out of Utah State. He's taller (6-foot-5 to 6-2) and older (29 to 24) and just as good as Nwosu, who figured to step in for the now departed Melvin Ingram (who left for the Pittsburgh Steelers after nine seasons).

It's a heck of a battle.

"Kyler and Uchenna are really doing a good job for us," Chargers coach Brandon Staley said. "Both of them ... are going to be really big assets for us ... the specific roles that they play are still to be determined.

"The good thing is they're not different players and both can do jobs that both complement Joey Bosa."

Ah, Bosa. The key to the defense.

"To see how he's been so successful, most guys don't get the opportunity to learn from a Pro Bowler like that," Nwosu said. "So me being able to learn from him for four years and grow and be ready for this opportunity."

Said Bosa: "Kyler and Uchenna both have been doing a great job."

That doesn’t help the underlying question of who starts?

"That's my goal," said Fackrell, who has 20.5 career sacks, including 10.5 in 2018 with the Packers. "I know Uchenna and Joey are great players. It's hard to go 100% every snap, but we will have a decent rotation. I will be looking to contribute any way I can."

The beauty of this defense is Staley can insert different guys into different positions for no reason that we can tell (they know the secrets after all) but it's all designed to confuse the opposition. Having smart players who know how to play certainly helps.

Nwosu caught on quickly, watching a lot of Los Angeles Rams defensive tape (Staley was the defensive coordinator for the Rams before coming to the Chargers -- leading them to the No. 1 overall ranking last year), specifically of Rams outside linebacker Leonard Floyd.

"The versatility in this defense. Always being in the right situation at the right time," Nwosu said. "He has a lot of different ways to get in and out of different defenses, to make sure in the right call and playing our best. I'm really excited for that."

When asked about Fackrell, his competition: "He's been in the league for six years, so he's played a lot of ball. He has a lot of wisdom and intelligence behind him. ... I just can't wait to get on the field with him and together, see what we can do."

Indeed. But who starts?