The old adage that offense wins games but defense wins championships still hold true in modern-day football in the NFL. With several teams stacking up on offensive firepower, having a solid defensive line is equally important for their counterparts. The league has seen a handful of defensive groups that dominated the trenches in recent years and will continue to do so in the upcoming seasons.

Let's dive into the 5 most lethal pass rushing teams in the NFL:

5. Los Angeles Chargers

After settling their respective contract situations during the offseason, the defensive end duo of Joey Bosa and Melvin Ingram should be all systems go for the upcoming season.  The former Ohio State Buckeye in Bosa has already tallied three double-digit sack seasons in his four-year career. On the other hand, Ingram remains to be a consistent contributor for the Chargers and snagged his third straight Pro Bowl appearance last season.

However, the shallow depth on the team's defense became evident when no other Charger notched more than three sacks last season. The duo will need to get more help from their teammates if they want to make it as far as they could in the upcoming season.

4. San Francisco 49ers

The San Francisco 49ers may have fallen from last season's top spot on this list due to the departure of their most reliable defender in DeForest Buckner during the offseason. It also remains to be seen if 2020 first-round pick Javon Kinlaw will be able to live up to expectations and fill in the big shoes left by Buckner.

Despite this, the group is still a force to be reckoned with. They are headlined by sophomore star defensive end Nick Bosa who has already established himself as one of the league's best. His strong rookie campaign was capped off by the NFL Defensive Rookie of the Year award and his first Pro Bowl appearance last season.

Linebacker Dee Ford was only limited to 11 games in a backup role due to a knee injury but still managed to bag a Pro Bowl appearance last season. Six-year veteran defensive end Arik Armstead will also aim to replicate the same success he had last season as he contributed a career-best 10 sacks and 16 assisted tackles for the 49ers. 2017 3rd overall pick Solomon Thomas will also aim to have a breakout season as he enters the final year of his rookie contract.

The ultimate goal remains the same for the 49ers who will aim to reach the Super Bowl stage once again even with new faces manning the trenches in the upcoming season.

3. Chicago Bears

The Chicago Bears' frontline will continue to lean on defensive phenom Khalil Mack even though he was coming off a down year based on his standards, with an 8.5 sack tally last season. His sidekick in defensive tackle Akiem Hicks was only limited to five appearances in 2019 due to a knee and elbow injury.

The tandem gains another prolific member in veteran outside linebacker Robert Quinn. His previous campaign with the Dallas Cowboys saw him account for 26 total tackles, 11.5 sacks, and two forced fumbles in 14 games played. He will look to ease in the starting rotation and give a huge boost to the Bears' defense in the upcoming NFL season.

2. Denver Broncos

The Denver Broncos are about to welcome an elite trio of pass-rushers in the upcoming season. The defensive line is still headed by the ever-reliable linebacker Von Miller who was in his usual dominant form which gave him his 8th Pro Bowl trip last season.

Pairing with Miller is third-year edge rusher Bradley Chubb who will see a bigger role on the defense after a partially torn ACL injury sidelined him for the majority of 2019.

The final piece of the puzzle is veteran defensive end Jurrell Casey who saw significant success in his position in recent years. His solid contribution previously for the Tennessee Titans earned him a second-team All-Pro selection and a total of five Pro Bowl appearances.

Mile High will see if the newly-formed defensive unit will increase the Broncos' chances of making a playoff push in the upcoming season.

1. Pittsburgh Steelers

Defense has always been the name of the game for the hard-hitting Pittsburgh Steelers. It has been the team's brand ever since the 1970s until today. The prolific trio of defensive end Cameron Heyward along with outside linebackers T.J. Watt and Bud Dupree headline the modern-day Steel Curtain in Pittsburgh.

The group has been a force in the league in recent years, leading the NFL in sacks for three straight years. Heyward is a ten-year veteran who saw multiple Pro Bowl trips and first-team All-Pro selections over the years. Watt is an edge rusher on the rise who tallied career-high numbers last season in 20 assisted tackles, 14.5 sacks, 36 quarterback hits, 2 interceptions, and 8 pass deflections through 16 games played.

Six-year veteran Bud Dupree also had his moments last season where he had a breakout campaign for the undermanned Steelers. He recorded career-highs in all areas on the stat sheet in 2019, further establishing himself as a major part of the team's defensive line. The upcoming season will also feature the recently-injured defensive end Stephon Tuitt and along with rookie outside linebacker Alex Highsmith.

The league's best defensive rotation will aim to limit opposing offenses and bolster the team's chances of making it deep into the playoffs in 2020.