If Mitchell Trubisky handles the Vikings defense the same way he’s dealt with the hoopla surrounding his first NFL start, he’ll have a successful debut Monday night.

“I think he’s done tremendous,” coach John Fox said Saturday. “I think he’s done tremendous since he’s been here. It’s been said numerous times. It’s no different this week. He’s put everything he’s got into it and that’s really all you can ask.”

John Fox

While Trubisky’s promotion has seemingly provided a spark at Halas Hall, it’s too early to tell whether it will help fuel a resurgence following the Bears’ 1-3 start.

“It’s hard to say,” Fox said. “I don’t think it’s always about one guy. Guys are excited, myself included, to watch him play in an NFL regular-season game. He’s had a great week of preparation. We’ll find out Monday night.”

Injury report: Inside linebacker Nick Kwiatkoski (chest) and outside linebacker Willie Young (triceps) both did not practice Saturday and are listed as doubtful for Monday night’s game against the Vikings.

Young is in jeopardy of missing only his third game in four seasons with the Bears.

“Any time you lose a starter I think there’s a reason they’re the starter, but I feel good about our backups,” Fox said. “I feel good about the replacement people we’ve had in there. We’ve got more depth this season than we’ve had in the past, so I feel confident in the people we’ll have out there and the options we have.”

Cornerback Marcus Cooper Sr. also did not practice Saturday and is questionable for Monday night’s game. “He had some back spasms,” Fox said. “We’ll kind of assess it and see how he looks tomorrow.”

Center/guard Hroniss Grasu (hand) is also questionable after being limited in practice Saturday.

Timu time: With inside linebacker Danny Trevathan set to serve his one-game suspension Monday night following his illegal hit on Packers receiver Davante Adams, John Timu is expected to start and call the defensive signals.

Timu has appeared in 20 games with eight starts in three seasons with the Bears since arriving in 2015 as an undrafted free agent from Washington.

“Experience helps at all positions and typically regardless of your job description the more you do it the better you should get,” Fox said. “John’s got a great understanding of our defense. He understands a lot of the calls and checks, so obviously there’s a comfort level with him being out there having been with us for some time.”

Looking at Leonard: Second-year pro Leonard Floyd has recorded 11 tackles and one sack in the first four games of the season. Asked about the 2016 first-round pick’s performance, defensive coordinator Vic Fangio said: “It’s been fine.

“He’s had his good moments and not so good. He played the first week or so with a little wrenched back that affected him some in the first game and some of the second game. I thought he played well against Pittsburgh. And then last week none of us played well enough to win [in Green Bay]. The game got out of hand there.”