SANTA CLARA, Calif. -- Two weeks into the 2018 season, San Francisco 49ers running back Matt Breida leads the NFL in rushing.

Just like everyone (alternatively: no one) expected, Breida's 184 yards on the ground are the highest total in the league, as is his 8.4 yards per carry average. Those numbers include Breida's big game Sunday against the Detroit Lions, in which he carried 11 times for 138 yards, including a 66-yard touchdown run in the second half.

After losing Jerick McKinnon to a season-ending knee injury, Breida, who came to the 49ers as an undrafted rookie from Georgia Southern in 2017 and quickly won the role as the backup to Carlos Hyde, has used those who didn't believe he could play a major role in the offense as motivation.

"A lot of people thought this year that I wasn’t going to get as much playing time as I did last year, and they planned on using both of us [Breida and McKinnon] a lot," Breida said. "It sucks that Jet went down, but I feel like me and him are going to be able to help this team out a lot and have a great year."

Although Breida's early-season success is almost certainly unsustainable, that doesn't mean it shouldn't garner him more opportunities than he has gotten so far.

Among the 21 running backs with 100 or more rushing yards through the first two weeks, Breida's 22 carries are tied for the second-fewest in the group. Such is life in the time share the 49ers have established between Breida and veteran Alfred Morris.

That work load has been almost dead even, though Morris has had more opportunities despite being less productive. Breida has played 52 snaps and has four catches for 26 yards. Morris has played 59 snaps with 26 carries for 86 yards, an average of 3.31 yards per attempt. He also has two catches for 32 yards and a lost fumble.

Breida, meanwhile, has looked increasingly comfortable in his second season in the Niners' outside-zone run game. That scheme asks its runners to make one decisive cut and get up the field quickly. If blocked properly and the runner is patient enough to see and hit the right hole, it can lead to big chunks of yards before defenders can get their hands on him.

Breida's 137 yards before contact and average of 6.23 yards before contact per carry both rank at the top of the NFL through the first two weeks. His five runs of 10 or more yards are tied for second among all players, one behind Carolina quarterback Cam Newton. Even if you take away Breida's 66-yard touchdown run, he is averaging a robust 5.6 yards per carry.

What Sunday's win against the Lions made clear is that Breida offers an explosive element to the offense more akin to what McKinnon can do.

“I think him and Alfred have their strengths," fullback Kyle Juszczyk said. "I think Matt is very explosive, and I think Alfred does a great job of turning out those ugly yards. He is always falling forward. That is not to take away from either of them. They both do both well, but I definitely think those are the strengths of those two guys.”

Since McKinnon’s injury, Niners coach Kyle Shanahan has indicated that the running back situation will be sorted out over time. Two weeks in, roles seem to be crystallizing, and while there's certainly still room for Morris, Breida should probably start getting more chances based on early production.

After Breida's long touchdown run against the Lions, he got only one more carry the rest of the game. Morris got seven and picked up 29 yards. Asked why Breida got less work after his big play, Shanahan pointed to Morris' fit in the four-minute offense. The idea is that Morris is better suited to churn out tough yards that can move the chains and milk the clock.

“When you get into a four-minute drill, and you’re trying to run the clock out -- we needed about two first downs to end it, I believe it was -- you want to get a bigger guy in there just a little bit better with the arm tackles,” Shanahan said.

Indeed, Morris' track record in such situations is much greater, but just because Breida isn't as big as Morris doesn't mean he isn't capable of picking up those tough yards. According to ESPN Stats & Information, Morris is eighth in the league in yards per carry up the middle at 4.33. Breida is close behind at 4.17, which is tied for ninth.

Breida has also showed an ability to pick up yards after first contact. He has averaged 2.14 yards after contact per rush, which ranks 13th in the league. Morris is averaging 1.35, which is 40th among qualified backs.

As the Niners continue to consider their options in the run game, it isn't crazy to suggest that Breida's role should continue to expand. That doesn't mean he should suddenly get 25 carries per game, but an uptick in his opportunities would be warranted based on how started the season.

"I'd like to get everyone more opportunities," Shanahan said. "… Usually the better you're playing, the more runs you get. The better you do on third down, the more you control the ball. We'd love to get 50 carries in a game here, but we'll have to get after someone to do that."