ALAMEDA – The Raiders completed the first day of mandatory minicamp on Tuesday, a long session loaded with situational football. Head coach Jack Del Rio wanted to test his players and help ensure they are ready to go come training camp, when football activity ramps up for the fall.

“(We are) putting them in different situations here, as you saw at the end, with four-minute, two-minute drills,” Del Rio said. “Those situations that you come in are so much a part of our league and being able to play well in those situations at the end, we’ll get a lot of work here in this camp and then into our training camp as well.”

The Raiders made solid use of this day, with plenty of encouraging periods to start this three-day stretch of practices and meetings.

Here are 10 observations and anecdotes from Tuesday’s opening session:

1. Nelson, Autry still missing

Safety Reggie Nelson remains out with injury, and hasn’t been present for any offseason workout open to the press. Same can be said for Denico Autry, who is also hurt.

“Everybody is doing what they can right now,” Del Rio said. “They’re working hard in the classroom and we have walk-thrus and things. Those guys are mending and working hard to get back.”

2. AC/DC chemistry

Carr and receiver Amari Cooper had an excellent day, connecting on a few big plays in practice. Carr consistently hit Cooper in stride – in fairness Sean Smith broke up one deep pass -- and the duo looked pretty dynamic for this stage in the offseason. Their chemistry and ability to make adjustments will be key to offensive success in 2015. They did that midway through Tuesday’s session, when Cooper made a double move outside and Carr found him for a big gain.

3. Crabtree coughs one up

Receiver Michael Crabtree never fumbles. He hasn’t lost a fumble since his rookie year in 2009 and the ball has left his grasp twice in seven seasons. He got caught by surprise following a reception from quarterback Derek Carr, when the ball came loose and Bruce Irvin scooped it up and scored.

Crabtree returned to the crime scene a few plays later and asked the practice official, “are you sure that didn’t bounce out of bounds?”

4. Edwards Jr. returns

Defensive end Mario Edwards Jr. practiced fully for the first time suffering a neck injury late last year, and hopped right back in with the first unit. He frequently played with tackle Justin Ellis and end Jihad Ward on the line, and looked active and strong for his first session back.

[BAIR: Edwards Jr.: 'I kept my faith' returning from sprained neck]

5. Other injury updates

First-round draft pick, safety Karl Joseph, continued getting work on the side, as he has during the offseason program. Cornerback Neiko Thorpe and linebacker Neiron Ball join him on the side as they continue to return from injury.

Dan Williams was a full participant in practice after leaving other OTAs open to the press after stretching and individual drills. Undrafted receiver Jaylon Mickens joined the squad. He wasn’t allowed to practice until finishing school at Washington.

Tight end Clive Walford was present on the field but remains out with a knee injury.

6. King shows power

Punter Marquette King has a powerful leg, and showed that with deep shots into a heavy wind during practice. A pair of punts were tipped at the line, but King showed power and consistency in special teams sessions that suggest he will continue last season’s excellent work.

7. Hayden in the slot

DJ Hayden was first unit’s primary slot cornerback on Tuesday, as he had been at other times during the offseason program. TJ Carrie is also in the mix for that job, which should be one of the position battles to watch in camp.

[BAIR: Norton: Raiders secondary improved; Joseph a 'pack of dynamite']

8. Battle at right tackle

Menelik Watson and Austin Howard shared time with the first-unit, though Watson seemed to get more work. Howard is recovering from a knee injury, but the two will battle for a starting spot this preseason.

9. Mack overpowering

Khalil Mack was his usual, dominant self on Tuesday, with sacks, pass deflections and quarterback pressure during team drills. It’s hard to evaluate line play without pads, but Mack’s speed and agility is overwhelming despite being a power rusher.

10. Plays of the day

Undrafted free agent receiver Joe Hensley had another strong day, and sealed the practice with a big play. He broke free on the left sideline, caught a deep ball from Matt McGloin and flashed breakaway speed for a touchdown. Linebacker Ben Heeney also intercepted a tipped pass in practice. Irvin’s scoop-and-score also ranked high in a productive unit.