SANTA CLARA, Calif. -- Running back Marcus Lattimore will begin practicing on Wednesday, San Francisco 49ers coach Jim Harbaugh said Monday as the team reconvened from its bye week.

Lattimore, who suffered a devastating right knee injury, has yet to make his NFL debut after being selected by the 49ers in the fourth round of the 2013 NFL draft out of South Carolina.

As such, Lattimore's 21-day window to either be activated to the Niners' 53-man roster or be placed on season-ending injured reserve will begin that day as well.

It has been a long road for Lattimore, who said he would have to control his emotions come that first practice.

"But I've also got to go out there and be myself," Lattimore told the Associated Press. "Run like I know how to run and just go out there and play football."

Lattimore also said it would be a "big moment" when he finally does practice.

"Just try to put together a couple consistent practices," he said, "just so they know I'm good and they trust me to go out there and play. It’s been a long time, but I'm excited about it. It's going to be fun.

"It’s a blessing, that's what it is.”

Technically, Lattimore could be activated as soon as this weekend, before the Niners' home game against the St. Louis Rams on Sunday, and as late as the Tuesday before the 49ers play host to Washington on Nov. 23.