Fantasy football injuries are becoming a major concern with the playoffs rapidly approaching. One key injury this week comes in Denver, where running back Melvin Gordon is not expected to play when the Broncos travel to Kansas City. Gordon's absence creates an opportunity for rookie Javonte Williams, who has scored at least 11 PPR points in two of his last three games. Williams had 14 carries for 54 yards and a touchdown against the Chargers in Week 12, but how high should he be in your Fantasy football rankings?

Williams also has upside in the passing game, tallying three receptions for 57 yards against the Chargers. Should he be part of your Week 13 Fantasy football strategy? Before you lock in your Week 13 Fantasy football picks, be sure to check out the Week 13 Fantasy football predictions from the proven computer model at SportsLine.

When it comes to ranking players, SportsLine's model beat human experts in Fantasy football for the past several seasons especially when there were big differences in ranking. Over the course of a season, that could literally be the difference between winning your league or going home emptyhanded.

Last week, the model was extremely high on Buccaneers running back Leonard Fournette, ranking him as an RB1 for Week 12. The result: Fournette piled up 131 scrimmage yards and scored four touchdowns in a Buccaneers win. Anybody who had him in their lineup was well on their way to a huge week.

Now, the model, which simulates every NFL game 10,000 times, has revealed its Fantasy football rankings for Week 13 of the 2021 NFL season. Head to SportsLine now to see them.

Top Week 13 Fantasy football picks 

One player the model is high on this week: Vikings running back Alexander Mattison. Minnesota running back Dalvin Cook will miss his third game of the season due to a shoulder injury. Fortunately for the Vikings and Fantasy owners, Mattison is one of the best backup options in the NFL. He replaced Cook in Week 3, rushing for 112 yards and adding 59 receiving yards in a 30-17 win.

Mattison got another opportunity in Week 5, going over 100 rushing yards once again. The Vikings are willing to give Mattison as heavy of a workload as Cook, which makes him a valuable Fantasy asset in Week 13. SportsLine's model has Mattison listed ahead of running backs such as Josh Jacobs and Saquon Barkley this week.

And a massive shocker: Seahawks wide receiver Tyler Lockett, who was started in 88 percent of CBS Sports Fantasy football leagues last week, stumbles big-time and doesn't even crack the top 25 at his position. After putting up over 100 yards in his first two games and then only topping 35 yards once in his next five contests, Lockett has had at least 96 yards in three of his last four games.

However, target volume remains inconsistent for the seventh-year veteran. Lockett has only been targeted eight times or more on four occasions this season and he's been targeted five times or fewer in six games. Now ,he'll take on a San Francisco defense that has allowed only four 100-yard receivers all season and limited Lockett to four catches for 24 yards in Week 4. 

How to set Week 13 Fantasy football rankings

The model is also calling for an under-the-radar quarterback to finish in the top six of its Fantasy football rankings, ahead of players like Lamar Jackson and Josh Allen. This pick could be the difference between winning big and going home with nothing. You can only see who it is here.

So who should you start and sit this week? And which surprising quarterback could lead you to victory? Visit SportsLine now to get Week 13 Fantasy football rankings for every position, plus see which QB is going to come out of nowhere to crack the top six, all from the model that has out-performed experts big-time.