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It's time to make some last-minute adjustments to your Week 4 fantasy football roster. Often times, selecting the right quarterback can be a difference between a win and loss.

While starting someone like Peyton Manning is a no-brainer, other choices are a lot harder to make.

I'll make the decision for you, giving you the best and worst QB plays of the weekend.  

Good Play: Philip Rivers

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Philip Rivers has been really good this year. He's thrown for 798 yards, eight touchdowns and only one interception. He has an impressive 70 percent completion rate and is second only to Peyton Manning in touchdown passes.

He's going up against a Dallas Cowboys defense that struggles against the pass. They give up 274.7 yards per game, which is 23rd in the league.

But consider this—the Cowboys forced six turnovers against the New York Giants. Two of those turnovers were returned for touchdowns. And yet, they still gave up 31 points and allowed 450 yards passing, including a 70-yard bomb to Victor Cruz for a touchdown.

What if the Cowboys had only, say, three turnovers? Eli Manning would have thrown for 550 yards. 

The Cowboys won't cause six turnovers this week. Rivers has been one of the best quarterbacks in football this season, and he's renewed his chemistry with Antonio Gates. He has the ability to put up huge numbers this week and is a must-start. 

Bad Play: Eli Manning

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Eli Manning has been sacked 11 times, and the Kansas City Chiefs lead the league in sacks.

Oh, and he is playing with a makeshift offensive line. Starters Chris Snee and David Baas are out, and David Diehl is doubtful. Here is what Ralph Vacchiano of the New York Daily News thinks the starting offensive line is going to look like:

That's not even close to resembling a good line. James Brewer was awful against Dallas, and Jim Cordle is barely passable as a lineman in special-teams situations.

Quite simply, Kansas City's Justin Houston, Dontari Poe and Tamba Hali are going to have a field day. The Chiefs top the league in sacks with 7.5, and Poe is in the top 10, with 3.5. Manning is not going to have any time to throw.

Even if he does find some time to throw, the Chiefs secondary is going to lock receivers down. They give up just 185 passing yards per game, which is fifth best in the league. 

It's going to be a long day for the Giants. Accordingly, you have to avoid Manning at all costs. He's questionable even as a QB2 and should only be used in emergencies. 

Good Play: Terrelle Pryor

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Despite suffering a concussion last week, Vic Tafur of The San Francisco Chronicle reports that Terrelle Pryor will start against the Washington Redskins:

However, Adam Schefter of ESPN is now reporting that Matt Flynn, not Pryor, will start. 

Obviously, tread carefully and don't make a decision until the last minute.

If he does end up playing, he has the potential for a big game. The Redskins defense is atrocious. They are ranked 31st in pass defense, giving up 333 yards per game, and they are ranked 31st in rush defense, giving up 155 yards per game.

In other words, expect a monster game for Pryor. He has actually been really good this year. He's thrown for 624 yards, and his 65.4 completion percentage is 11th best in the league. He's also rushed for 198 yards, which is 13th best in the league. His 7.6 yards per carry is the best in the NFL among those who have more than six carries per game, per ESPN.

There is a risk that the lack of practice and any lingering effects from the concussion will hold him back. 

But the Redskins defense is just so bad. Michael Vick threw for 203 yards and ran for 54 yards in Week 1. Many of his rushing yards were taken away by LeSean McCoy, who ran for 184 yards.

Darren McFadden is not McCoy. The Raiders are going to ask Pryor to do a lot of the running. And because the Redskins couldn't stop a snail, Pryor is going to go off.