Defensive day: The Detroit Lions held an evening practice at the Meijer Performance Center Monday, conducting a mock scrimmage with the first-team offense and second-team defense joining forces on the scoreboard against the first-team defense and second-team offense.

I thought both defensive units were terrific Monday, making a ton of plays. Between them, I charted seven sacks, three interceptions and a defensive touchdown on edge rusher Eric O’Neill's pick-six.

Gaining steam: O'Neill recorded that pick-six when he got his hand on an attempted screen pass by quarterback Luke Altmyer and tipped it to himself at around the five-yard line before running into the end zone. He also had a sack.

O'Neill had a tackle for loss and quarterback hit in the Lions' preseason debut last Thursday. The undrafted rookie out of Rutgers has had a nice few days here and said after Monday's practice that it's all about continuing to stack good days on top of each other as he makes a big push for the 53-man roster or practice squad.

Have a day: Third-year cornerback Ennis Rakestraw Jr. had a nice scrimmage Monday, recording a tackle for loss, an interception and a pass breakup. He allowed one touchdown on a short slant to wide receiver Tom Kennedy, but Amon-Ra St. Brown ran a good pick on him to help free Kennedy for the touchdown. Overall I thought it was a nice practice for Rakestraw coming off an uneven performance in the preseason opener.

A couple other good defensive performances worth note: Linebacker Trevor Nowaske (two sacks) and linebacker Devin White (one sack and multiple tackles).

Touchdown receptions: Besides the Kennedy touchdown, tight end Sam LaPorta had a 25-yard touchdown on a good misdirection bootleg play. The other touchdown for the offense was a 19-yard pitch and catch from Altmyer to wide receiver Lucky Jackson down the right sideline.

Opportunity for Abney: Rookie fifth-round pick Keith Abney II has started taking first-team reps at the nickel cornerback spot the last few days. He was good in his preseason debut last week. He had a couple nice plays in coverage Monday, one in particular on St. Brown on an early 3rd & 5 play to force an incompletion and a punt. Abney, Roger McCreary and Christian Izien look to be in a pretty good battle for the nickel role.

Running back prowess: Sione Vaki has become one of Detroit's best special teams players over the last two seasons. Entering Year 2 he's hoping to earn some more offensive reps as the No. 3 running back. That part of his game is certainly coming along. Don't forget he was a safety in college who converted to running back late because of injury issues, so he doesn't have a ton of experience. Vaki had a nice jump cut to find some running room early in practice. There were a couple tough runs between the tackles for good gains too. Later in practice, he bounced a run out to the right for a 19-yard gain that ultimately led to a short field goal.

St. Brown vs. Sheppard: St. Brown and defensive coordinator Kelvin Sheppard are as competitive a player and coach as you'll see in a practice setting. Sheppard is always chirping and trying to rile his defenders up. St. Brown is never one to back down from a challenge. The two went back and forth a couple times Monday night with St. Brown being sure Sheppard was the first to know when he made a catch. Same thing when Sheppard's defense made a play on St. Brown. That healthy competitive banter seemed to fuel both guys Monday night.

Playing referee: Head coach Dan Campbell talked Sunday about never wanting to relinquish control of the red flag, which the NFL is allowing head coaches to do this season if they want to give the duty of tossing the challenge flag to an assistant.

"Look, the buck stops with me anyway. I'm answering the questions, so why would I give it to somebody else for me to answer for somebody else?" Campbell said. "It all comes to me anyway. And so yeah, that's it."

Campbell added a yellow flag to his repertoire Monday as he played lead official calling out penalties on both sides when he spotted them.

Long drive: The best drive of the day for the first-team offense was late in the scrimmage when quarterback Jared Goff led a 14-play drive from the 29-yard line down to about the six-yard line. The offense picked up a couple third and longs on catches by wide receiver Isaac TeSlaa and running back Jahmyr Gibbs but eventually had to settle for a short field goal after stalling inside the 10-yard line.