The San Francisco 49ers will begin the 2013 NFL season against the Green Bay Packers this Sunday.

Expectations of the NFC West champions are high, following their narrow Super Bowl defeat to the Baltimore Ravens earlier this year.

Sports Mole takes a look at 49ers' off-season changes, pre-season performances and key players:

Head coach: Jim Harbaugh will continue to lead the team for a third season. The arrival of the former Stanford coach at Candlestick Park ended a run of eight years without a playoff place for the five-time Super Bowl winners. Harbaugh has guided the 49ers to the top of the NFC West division in his first two years with the team, and will be looking for his hat-trick in 2013. The 49ers' defeat to the Baltimore Ravens, who are coached by Harbaugh's brother John, was the franchise's first Super Bowl defeat. The former Bears and Colts quarterback will surely be looking to go one better this season.

Last season: 11-4-1

Review: Having reached the NFC Championship game the season before, the 49ers were one of the favourites to win the Super Bowl heading into the 2012 season. The side seemed to cope well with the weight of expectation at the start of the season, winning six of their opening eight games. Colin Kaepernick replaced Alex Smith at quarterback in the second half of the campaign, recording good wins over the Chicago Bears, New Orleans Saints and New England Patriots. However, the second-year passer struggled against divisional opponents, particularly during the team's week 16 defeat to the Seattle Seahawks. The 49ers had been regarded as a strong defensive side with a good running game, but 2012 saw the team pose a threat with their passing game. The 49ers were impressive in their post-season wins over the Atlanta Falcons and Green Bay Packers, but gave the Ravens too big a lead in the Super Bowl, allowing their opponents a 28-6 lead before fighting back.

Notable Ins: The 49ers agreed a trade with the Ravens to bring in wide receiver Anquan Boldin ahead of the start of free agency. The move could prove vital, as last year's leading receiver, Michael Crabtree, suffered an Achilles tear during minicamp. The 32-year-old posted impressive figures during his final season with the Ravens, recording 921 receiving yards in the regular season, adding a further 380 in the post-season. Another key acquisition for the 49ers will be kicker Phil Dawson. The veteran had an average field-goal completion rate of 84% during his 14 seasons with the Cleveland Browns. Kicker was a position that caused problems for the 49ers last season, with David Akers missing more attempts than any other player at his position in the NFL.

Notable Outs: One of the first players to leave the 49ers during the off-season was former starting quarterback Alex Smith. The 2005 top Draft pick was traded to the Kansas City Chiefs in exchange for their second-round Draft pick. Although Smith would not have ousted Kaepernick from the starting role this year, his departure has left the team without an experienced backup. Delanie Walker and Dashon Goldson also left the team as free agents this summer. The tight end signed with the Tennesee Titans, while Goldson joins the Tampa Bay Buccaneers. Although neither were regular starters with the 49ers, their departures leave holes in the team's depth charts.

Key Player Offense: Colin Kaepernick: The quarterback may have less than half a season as starter with the team under his belt, but his performances will be crucial if the team are to reach the Super Bowl again this season. With the read-option offense becoming ever-more popular, Kaepernick's ability to run the ball as well as make passes will test the best of defenses. The 25-year-old struggled against the Seattle Seahawks last season, but will have a chance to prove that he learned from the experience in the second week of the season. Kaepernick was used sparingly during the team's pre-season, but looked to be in good form, completing 171 passing yards from 15 completions, including two touchdown passes, with no interceptions or sacks.

Key Player Defense: Justin Smith: Aldon Smith may have led the team in sacks last season, but the linebacker was almost anonymous in the final two games of the regular season, which Justin Smith missed with a triceps injury. The 49ers recognised the defensive end's value during the off-season, rewarding him with a two-year contract extension. The 33-year-old made 47 tackles, 19 assists and three sacks last season, many of which allowed Aldon Smith to get at the opposing team's quarterback. Smith underwent triceps surgery earlier this year, but is back to full fitness heading into this season.

Rookie to watch: Quinton Patton: As a fourth-round Draft pick, Quinton Patton did not steal the headlines as he joined the 49ers earlier this year, but the wide receiver has shone during the team's pre-season games, hauling in a 43-yard touchdown against the San Diego Chargers last week, finishing the pre-season with six receptions, 36 receiving yards and two touchdowns. With Michael Crabtree's injury, and the departures of Randy Moss and AJ Jenkins, Patton could be in for a strong rookie season.

Pre-season form: The 49ers narrowly lost their pre-season opener to the Denver Broncos, in a game where both sides rested their starters. However, the return of the first team has seen the NFC West champions win their final three games in August, including a 41-6 destruction of the Chargers last Thursday. Jim Harbaugh's team should be heading into the regular season full of confidence.

2013 prediction: The 49ers are expected to face stiff competition for the NFC West title from the Seattle Seahawks this season, having claimed the division by just half a game last year. Should the 49ers not win their division, they will be a strong candidate for a wildcard place in the playoffs, where experience from the last two seasons should serve them well. The 49ers are definitely contenders to reach the Super Bowl again this season.