Injuries are a weekly fact of life in the NFL -- as are second-stringers stepping up to fill the void.
Week 4 was no different, with San Francisco 49ers quarterback Jimmy Garoppolo and Chicago Bears running back David Montgomery both going down with ailments that at least could sideline them in Week 5.
Both of their backups are widely available on the fantasy football waiver wire, which has a few more intriguing options who could make an impact in the coming weeks.
Here are five players worth picking up off the waiver wire in Week 5, all of whom are rostered in fewer than 50% of Yahoo fantasy leagues.
Trey Lance, QB, San Francisco 49ers (31% rostered)
Garoppolo said he hopes to only miss "a couple weeks" with his calf injury. That means the rookie Lance -- who racked up 157 passing yards and two touchdowns with 41 rushing yards in a single half Sunday -- is in line to start against the Arizona Cardinals.
This game should be a shootout, and Lance's running ability gives him a low-end QB1 floor. He should be added in all formats.
Damien Williams, RB, Chicago Bears (8% rostered)
Williams seized his opportunity after Montgomery's injury Sunday, rushing for 55 yards and a score while adding a pair of catches.
If Montgomery can't go in Week 4, Williams should be Chicago's top running back against a Las Vegas Raiders team allowing 132.3 rushing yards per game. He's the top waiver wire option at his position this week.
UPDATE (Oct. 5, 9:30 a.m. ET): Montgomery is expected to miss four to five weeks with a knee sprain. Needless to say, Williams is the guy you want to add.
Kenneth Gainwell, RB, Philadelphia Eagles (29% rostered)
While Miles Sanders stumbled to just 13 yards on seven carries Sunday, Gainwell racked up 89 total yards on nine touches, six of which came in the passing game.
The Eagles' run game outside of Jalen Hurts is atrocious, but Gainwell looks like the preferred receiving option out of the backfield, giving him legitimate FLEX upside in half- and full-PPR leagues.
Curtis Samuel, WR, Washington Football Team (40% rostered)
Scoop him up while you can, folks. Samuel had a quiet day in his return from injured reserve Sunday with four catches for 19 yards.
But the former Panther was signed to be the No. 2 option in the passing game behind Terry McLaurin, and with tight end Logan Thomas potentially missing time, the production will come. Samuel should starter-worthy in a matter of weeks.
Dalton Schultz, TE, Dallas Cowboys (34% rostered)
Schultz and Dawson Knox are both rostered in fewer than 50% of Yahoo leagues, but Schultz is the guy you want. He's tallied six receptions in three of his first four games and ranks third on the Cowboys in targets behind Amari Cooper and CeeDee Lamb.
Schultz should continue to see a steady diet of targets from Dak Prescott, and that consistency is immensely valuable at tight end.