The Kansas City Chiefs returned to practice on Wednesday with the season-opener against the Jacksonville Jaguars just a few days away.

In terms of injuries, safety Tyrann Mathieu (shoulder), safety Armani Watts (shoulder), tailback Darrel Williams (shoulder) and tight end Deon Yelder (ankle) were all full participants in Wednesday's practice.

Prior to practice, Head Coach Andy Reid, quarterback Patrick Mahomes, tight end Travis Kelce and defensive tackle Chris Jones met with the media to discuss the onset of the regular season.

Here are five things that stood out from their pressers.

1. Reid began by explaining the challenges that the first game of the season presents, especially when it's against a team like Jacksonville with so many new faces on the offensive side of the ball.

The Jaguars made some big additions this offseason, including a pair of former Chiefs in quarterback Nick Foles and wide receiver Chris Conley. There isn't much tape on Jacksonville's new weapons, creating an intriguing task for Kansas City's defensive staff.

"The defensive coaches have gone through and looked at [everything], but you have to cut it down," Reid said. "There are going to be things that you haven't seen [where] you just have to trust your fundamentals, technique, scheme and rules. They've looked at all of that."

2. Speaking of additions, Sunday's game will mark the first action for new Chiefs' tailback LeSean McCoy. Reid discussed how quickly McCoy has been picking up the playbook during his brief time in Kansas City.

"He has done a good job with it. These practices will be important, but he seems to be picking it up pretty quickly," Reid said. "There's a learning curve there, but the gameplan is narrowed down enough to where he can learn it. We just have to get through the rest of the practices so that he has a chance to practice them."

McCoy adds another dynamic piece to an already potent offense, rounding out an impressive backfield alongside Damien Williams, Darwin Thompson and Darrel Williams.

Reid went on to explain how much fans should expect to see of McCoy on Sunday.

"Yeah, in some form I think he will [play]. Physically, he's good," Reid said. "It's just that I'm trying not to put him in a bad position. We have enough good players, so we're OK there, but I'll let you know the closer we get. I might not let you know, but I'll know."

3. Mahomes, meanwhile, talked about how last year's matchup with Jacksonville has aided his preparation for Sunday's game.

The Chiefs defeated the Jaguars last season, 30-14, at Arrowhead Stadium behind Mahomes' 313 passing yards.

"You definitely have notes. You have to watch the game a couple of times to see how they went about it, what they had success with and what we had success with," Mahomes said. "I think the biggest thing is knowing that they have adjustments, you will have to make adjustments on the fly and [also] have adjustments going in with the game plan. Jacksonville has a great defense and guys at every position who can make plays, so you just play that chess match during the game, you take what's there and you take those shots that are there. That's something we're going to have to work on throughout the week and capitalize on during the game."

Mahomes and Kansas City's offense – which put together the third-best season of all-time in terms of points-per-game a year ago – also now finally has a chance to show off any new wrinkles they've added to the playbook.

"I'm definitely excited to be able to show all these plays we've been working on all through training camp and watch how they're going to work in a game," Mahomes said. "That's stuff we worked on all offseason - how we think we can exploit defenses and how we think we can go out there and have success based on stuff we did last year. I'm excited that we're about to go out there now and use the full game plan and do everything we need to do in order to, hopefully, come out with a win."

4. One of Mahomes' top weapons on offense is Kelce, who shared his excitement level for the upcoming campaign.

"I feel like it kind of goes up every single year. You have to up the ante, so to speak, and make sure that you bring something to the table that you didn't last year," Kelce said. "That's what you get all offseason to work on and to prepare for."

The prospect of Kelce getting even better is an exciting one, as the veteran tight end put together one the best seasons ever at the position in 2018 with 103 catches for 1,336 yards and 10 touchdowns.

And like Mahomes, the veteran tight end seemed pretty excited when asked about the new plays designed for him that aren't yet on tape.

"For sure. That's what makes the preseason difficult because you're like, 'Oh man, I hope Coach Reid doesn't dial up my play we're going to use during the season,' but you have fun every single week," Kelce said. "This offensive staff - and really this coaching staff - is going to put together a game plan that's going to get you excited and give you an opportunity to go out and showcase your ability. That's where I've had the pleasure of being here going on year seven being under Coach Reid and this offense and getting the opportunity every single week."

5. Finally, Jones discussed his feelings on the impending arrival of another football season.

"It's a little bit of [nervous excitement and calm] because you're excited to start the season. Everyone has those jitters when the songs are playing and when they have the first kickoff of the NFL season. Everyone is amped up and it's exciting," Jones said. "You finally get to hit someone else. You've made the 53-man roster and training camp is finally over, so there are a lot of positives."

Jones also touched on the Jaguars' offense and the challenge they'll present on Sunday.

"They added a few significant pieces. They took Chris Conley - a dynamic wide receiver and a good guy. Nick Foles, a championship quarterback and Super Bowl MVP. They have [tailback] Leonard Fournette. They have a lot of good weapons over there that they can build off of," Jones said. "We have to take that into account and prepare for that."

The Chiefs kick off the season on Sunday in Jacksonville.