The Cardinals enter Week Five as the only undefeated team in the 2021 NFL season, aiming to secure a 5-0 season start for the first time since 1974 when they play the 49ers Sunday. This marks the 39th meeting between the teams since becoming NFC West rivals in 2002.

As State Farm Stadium prepares to host its second home game of the year, here are five Cardinals to watch for in this week's spotlight.

Jordan Hicks

Fresh off another week of strong play by registering a season-high 12 tackles against the Rams, Hicks – who plays the "Mike" linebacker position – is another reason why the Cardinals' defense has meshed well. The unit has allowed 21.3 points per game this season, ninth in the NFL. Through four games, Hicks has 30 tackles and a sack while playing the majority of snaps. A matchup with a talented but inexperienced rookie quarterback in Trey Lance may result in a field day for Hicks and the Cardinals' defense.

J.J. Watt

Watt continues to have a productive season coming off a disruptive showing against the Rams. Capturing sack No. 1 as a Cardinal is the next thing fans await to see. The 49ers have allowed the fifth-least sacks this season, but Watt has pressured quarterbacks at a high rate. Watt nearly recorded his first sack on Matthew Stafford last week until the quarterback slithered away.

Milestone watch: With a sack, Watt would have his first against the 49ers, leaving the Rams, Patriots, Bears, and Texans as the only teams he has never registered a sack against.

Byron Murphy Jr.

Murphy is coming off another ball hawking performance against the Rams after his interception against Matthew Stafford. Opposing quarterbacks are completing just 50 percent of their passes against Murphy. He will certainly be tested with 49ers' wideout Deebo Samuel, who is enjoying a career-best start in 2021. Samuel leads the NFL with 490 receiving yards, and his 122.5 yards per game stands as the most in 49ers history, even above Hall of Famer Jerry Rice. This season, Murphy has shown why he is one of the best young cornerbacks in the NFL. Murphy is dealing with a ribs injury, which bears watching for both his availability and his effectiveness Sunday.

D.J. Humphries

Among the reasons Kyler Murray is enjoying an MVP-caliber start is because of the stout offensive line. Tackle D.J. Humphries plays a role in such success. Rising star Nick Bosa is next on Humphries' list of players to deal with. Since being drafted by the 49ers in 2019, Bosa has yet to record a sack when playing the Cardinals, showing that Humphries has fared well against the pass rusher. This season, Bosa is off to a fast start with 4.5 sacks and 15 quarterback pressures – both rank third in the NFL. Humphries will have his hands full.

Dennis Gardeck

After suffering a torn ACL Week 15 in 2020, followed by a year-long debilitating rehab process, Gardeck was finally activated to the 53-man roster in time to return vs. the Rams. The linebacker played just five defensive snaps, understandable in his first game back. It will be interesting to see how much playing time Gardeck receives on Sunday. But his speed off the edge could help against a player like Lance, and his presence makes the team's NASCAR package -- with Watt, Chandler Jones and Markus Golden -- one with potential.