The San Francisco 49ers Week 1 loss to the Chicago Bears was mightily disappointing. The 49ers were heavy favorites against a very weak Bears squad, but they ended up struggling mightily on offense throughout the game as torrential downpours made life difficult for both sides. Still, the weather cannot be used as an excuse to lose against a team as bad as the Bears.

As if losing the game wasn't bad enough on its own, the 49ers also lost their starting running back Elijah Mitchell in the contest with a sprained MCL, which will keep him on the sidelines for the next two months of the season. That's not great news for San Francisco considering they could use all the help they can on offense right now.

Fantasy football owners who were relying on Mitchell for production will be disappointed by his absence, but it also will open up an opportunity to find a sleeper option on the 49ers roster who could step up in his absence. With that in mind, let's look at the best fantasy football sleeper on the 49ers who should be on your roster for Week 2.

49ers Week 2 fantasy football sleeper

RB Jeff Wilson Jr.

With Mitchell on the mend, that will force Jeff Wilson Jr. into the spotlight for the time being. Wilson has been used as a starter at times filling in throughout his career, but he's often been wildly inconsistent. That's why he was being used as a backup to Mitchell to start the season, but now he will be forced to take on a larger workload with Mitchell out.

Wilson didn't make much of an impact against the Bears in Week 1, picking up just 22 yards on nine carries and eight yards on two catches. Granted he spent most of the first half on the sideline, but Wilson watched Deebo Samuel outproduce him out of the backfield while also playing wide receiver. Even with Mitchell out, it remains unknown whether or not Wilson will command the majority of carries out of the backfield.

Still, it's clear Wilson has upside if he's able to land the majority of the 49ers carries out of the backfield. Wilson has had some explosive games as a starter in his career, such as a 112 yard, three touchdown performance against the New England Patriots in the 2020 season or a game later in the 2020 season against the Arizona Cardinals when he racked up 204 total yards and a touchdown. It's clear Wilson can be an effective fantasy football option; it's just a question of whether or not he will be.

The potential for Wilson to explode is what makes him a necessary roster addition in Week 2 of the season. Wilson will be the lead running back for San Francisco, even if Samuel continues to slide over from wide receiver to take carries away from him. They will definitely split carries one way or another, we just don't know what that split is going to look like yet.

Wilson is still available in nearly 45 percent of fantasy leagues, and he has RB2 upside if he manages to get the majority of San Fran's carries. Playing him in Week 2 is going to be very risky, but he's not the worst FLEX option you will find on the free agent market. Even if Wilson doesn't get the majority of the 49ers carries, he has an increased chance of finding the end zone on a weekly basis now, and sometimes that's all you need from a free agent FLEX option.

We will find out a lot about Wilson's status moving forward over the next couple of months this week. He may not have a breakout game against the Denver Broncos in Week 2, but if he gets a decent amount of touches, he will immediately become a viable fantasy option. If you have a spot on your bench available, Wilson is a very good option to hold onto this week and see what happens against Denver.

For now, playing Wilson doesn't seem like a great idea. But if he can somewhere around 15 touches out of the backfield this week, that will be great news for fantasy owners who decided to take a flier on him in free agency this week.

Wilson is a very inconsistent and risky option out of the backfield, considering his iffy production and head coach Kyle Shanahan's odd deployment of his running backs, but his upside is clear as day. He may not pay off right away, but if you can land him this week, Jeff Wilson Jr. could end up becoming a very viable running back option while Mitchell is out, making him the 49ers top fantasy football sleeper this week.