The San Francisco 49ers, who dominated the Raiders last week, look for another stellar primetime effort on Monday Night Football when they host the New York Giants at 8:15 p.m. ET. While the Niners hope the momentum carries over, the Giants are coming off their bye week having dropped five in a row, the last two by a TD or less. New York is 1-7 straight-up and 3-5 against the spread, while the Niners are 2-7 straight-up and 3-6 against the spread. The latest Giants vs. 49ers odds have San Francisco favored by three points, up 1.5 from the opening line. The over-under for total points scored opened at 43.5, but is now 45. Before you make any Giants vs. 49ers picks and predictions, you'll want to see what SportsLine's Larry Hartstein is saying about the game.

SportsLine's senior analyst is 11-3 in his past 14 against the spread picks involving the 49ers -- he knows when to back them and when to fade them. That includes last Thursday night when Hartstein cited Oakland's porous defense as a reason to back the Niners -- and called for a big day from San Francisco's passing game. The result: Nick Mullens passed for 262 yards and three TDs in his first career start, a 34-3 rout. 

Moreover, Hartstein is a stunning 30-14 on all NFL spread picks this season, enabling his followers to net nearly $1,500. Now, he has pounced on what he calls a mistake in the Giants vs. 49ers line. He's only sharing his pick at SportsLine. 

Hartstein knows the Giants have just one win, but half their losses were by a touchdown or less. 

The offense has under-performed in large part because quarterback Eli Manning hasn't had time to throw. The two-time Super Bowl champion has been sacked a whopping 31 times, almost four per game, but when he's been able to get rid of the ball, he's completed 68 percent of his passes for 2,377 yards. Three-time Pro Bowler Odell Beckham has 61 receptions for 685 yards, ranking fourth and sixth in the NFL, respectively, entering Week 10.

Meanwhile, the bye week came at a good time for rookie RB Saquon Barkley, who averaged 73 yards rushing through the first six games, but has just 81 yards combined in the last two. He has nearly as many receiving yards (497) as rushing yards (519).

The Giants' defense showed considerable improvement its last two games, holding the high-octane Falcons to 23 points and the balanced Redskins to 20, led by a pass defense that ranks ninth in the NFL.

Even though the pieces are in place for New York to compete doesn't mean the Giants can stop the Niners from covering at home. 

The 49ers had lost six straight before tabbing Mullens as the starting QB. Last Thursday's 34-3 dismantling of the Raiders marked the team's highest-scoring effort this season. The Giants have 10 QB sacks -- only the Raiders have fewer -- so Mullens should have plenty of time to find receivers. 

San Francisco's run game has been a pleasant surprise all season, averaging 135 yards per game, fourth-most in the NFL. Second-year pro Matt Breida has 531 yards (5.5 per carry), while reserves Alfred Morris and Raheem Mostert have added 555 more yards.

The defense has 24 sacks, with the D-line taking care of business. Linemen DeForest Buckner (5.0 sacks), Cassius Marsh (3.5) and Ronald Blair (3.5) lead the way. 

We can tell you Hartstein is leaning over, but his much stronger play is against the spread. He says a crucial x-factor causes one side of the spread to hit hard. He's sharing what it is, and who to back, only at SportsLine. 

So which side of the Giants vs. 49ers spread should you jump on? And what crucial x-factor makes one side a must-back? Visit SportsLine now to see which side you need to be all over, all from the seasoned expert who's 11-3 on 49ers spread picks, and find out.