The San Francisco 49ers were the best team in the NFL well into October, but they don't hand out the Vince Lombardi Trophy in the second month of the season. After a brilliant start that saw the Niners win their first 5 games, they have lost their last 3 games and then had their bye week. That makes this week's game against the AFC South-leading Jacksonville Jaguars in Week 10 a most critical game.

The 49ers have not won a game in more than a month. Their last victory was a brilliant 42-10 victory over the Dallas Cowboys in Week 5, but since that game, quarterback Brock Purdy has come back to earth.

In addition to a slump by their second-year quarterback, ace wide receiver Deebo Samuel has missed 2 games with a shoulder injury. He has been a full participant in practice this week, and his return should give the Niners offense a major boost.

San Francisco has one of the most versatile and explosive offenses in the NFL. In addition to Purdy and Samuel, Christian McCaffrey is quite likely the best running back in the league, George Kittle is one of the top 3 tight ends in the league and Brandon Aiyuk is an excellent receiver who has proved to be very dependable in his tenure with the Niners.

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Beating a strong team like Jacksonville on the road is not an easy assignment, but the Niners can't let their losing streak stretch to 4 games if they want to be considered an elite team.

Brock Purdy will get back on track with 275 passing yards and 2 TDs

Purdy has not fallen apart, but after starting the season with a 9-0 TD to interception ratio in the first 5 games, the quarterback has thrown just 3 TD passes and tossed 5 interceptions in the last 3 games.

One of the reasons for Purdy's lack of consistency has been the absence of wideout Deebo Samuel, who has missed 2 games with a shoulder injury. Barring any kind of major setback prior to Sunday's matchup at Jacksonville, Samuel will be in the lineup.

Samuel has caught 20 passes for 302 yards and 1 touchdown and he also has 18 carries for 95 rushing yards. More than the numbers, Samuel plays with incredible toughness, and when he is healthy he will take on tacklers and win the battle.

The presence of Samuel makes every other player on the offense better, and that includes Purdy, tight end George Kittle and leading receiver Brandon Aiyuk.

The Niners have a multitude of options on the offensive side of the ball, and that will make life difficult for a Jacksonville defense that ranks 23rd in yards allowed.

The week off and the return of Samuel should Purdy get back on track in this game.

Christian McCaffrey should dominate 90-plus rushing yards and 2 TDs

While the Niners have had some recent difficulties on offense, head coach Kyle Shanahan and general manager have to feel great about the  contribution McCaffrey has made since he was acquired from the Carolina Panthers a year ago.

McCaffrey has been a touchdown machine since donning a 49ers uniform. He has scored at least 1 touchdown in every game he has been with the team, and he has 9 rushing touchdowns and 4 more as a receiver this season.

McCaffrey runs with speed, elusiveness and power, and he has gained 652 yards on 137 carries while averaging 4.8 yards per carry. He also has the hands to make difficult catches, having caught 32 passes for 292 yards.

The Niners need McCaffrey to have a big game against Jacksonville's vulnerable defense.

Linebackers Fred Warner and Dre Greenlaw must slow down Trevor Lawrence and Travis Etienne

The Jaguars has a pair of stars on offense in quarterback Trevor Lawrence and running back Travis Etienne.

If those two are allowed to get off to a good start, the Jaguars could push the Niners very hard in this game and turn it into a 60-minute battle that comes down to the late stages of the 4th quarter.

The Jaguars have the 14th-ranked offense in the league, and it will be up to Warner and Greenlaw to shut down Etienne in the running game and limit Lawrence from having a huge game through the air.

Warner leads the Niners with 71 tackles, 5 tackles for loss, 5 passes defensed, 2 interceptions and 2.0 sacks. Greenlaw is fairly close behind with 55 stops, 4 tackles for loss, 2 passes defensed and 1.0 sack.

The Niners rank 10th in yards allowed, and if they can put pressure on Lawrence with a much-needed pass rush, they should find a way to be successful here.