The San Francisco 49ers start an extremely intriguing 2018 season on Sunday when they take on the Minnesota Vikings. It will be a huge challenge against a team many view as Super Bowl contenders. It will also be the first game of the 49ers' Super Bowl window.

While many expect the Niners to contend for the playoffs in 2018, nobody is tipping them to be in a position to challenge to reach Super Bowl LIII in Atlanta. Yet the second Jimmy Garoppolo signed his five-year, $137.5 million deal, the the 49ers' Super Bowl window was open.

There is a consensus in the modern NFL that the biggest asset a team can have is a quarterback on a rookie contract. The 49ers do not have that. What they do have is a quarterback unbeaten in seven starts and a host of players at important positions on affordable contracts.

Jimmy Garoppolo's contract accounts for over 15.86% of the 49ers' salary cap in 2018. After that, the majority of San Francisco's money is committed to the offensive line.

The 49ers are spending 14.56% of their 2018 cap on the offensive line, but eight percent of that is committed to the contracts of Joe Staley and Weston Richburg, two elite options at left tackle and center, respectively. Right tackle Mike McGlinchey and Joshua Garnett -- more likely to be the long-term option at right guard than Mike Person — are both still on their rookie deals. Person aside, the 49ers' starting Offensive Line is signed through to 2020, when Staley's contract expires.

San Francisco will be using over $10 million of its cap on an injured running back in Jerick McKinnon, but it can get out of his contract this offseason should it wish. All of his cap hits from 2019 are below $8 million. Beyond McKinnon, the Niners are spending less than one percent of the cap on the remaining running back options, with Matt Breida still tied to his rookie deal.

One player dominates the Niners' spending at wide receiver, with San Francisco spending over $9 million of the cap on Pierre Garçon. However, the final three years of his deal are option years, giving the 49ers an out they will be more likely to use should rookies Dante Pettis and Richie James build on the great potential they displayed in preseason. Slot receiver Trent Taylor and Kendrick Bourne are also on rookie deals and Marquise Goodwin, who appears to have usurped Garçon as the No. 1 receiver, has an average salary of just $6.14 million. Starting tight end George Kittle has three years to go on his rookie deal, meaning the majority of Garoppolo's targets and those protecting him are locked to multi-year deals that have little impact on the cap relative to the substantial impact the likes of Goodwin, Taylor and Kittle have already made on the field.

It is a similar story on defense, as Richard Sherman's three-year, $39.15 million deal is incentive-laden and, though Malcolm Smith and Earl Mitchell are among the 12 highest-paid players on the team, the Niners can get out of the latter's contract in 2019, when the dead money will be less than the cap savings they would make by cutting him, and most of their key defensive contributors are on rookie deals.

DeForest Buckner and Arik Armstead are both in line for extensions, though the latter will need to show improved performance and durability to earn one, but Solomon Thomas, Reuben Foster, Ahkello Witherspoon and Adrian Colbert are all poised to occupy pivotal roles for the coming years while on rookie deals. The same cannot be said for Jaquiski Tartt, whose breakout year at strong safety was halted by injury, but at most he will take up 3.2% of the cap over the remaining three years of his contract, according to Over The Cap.

There are clear holes on this team, the most obvious of which is a lack of a talent of edge rusher, while there has to be questions over the depth at cornerback beyond Sherman and Witherspoon. However, through having much of its roster taken up by young players on rookie deals and the use of frontloaded contracts that the 49ers have the ability to get out of, San Francisco approaches 2018 with over $33.5 million of space.

In an NFL in which the cap continues to increase and there are numerous ways with which to engineer space, that number is likely to go up, giving the 49ers more outlay with which to fill the holes on the roster.

The widely held belief is that the 49ers are a year away from true contention. That may be the case, however, they have their quarterback and an exciting young roster being led by arguably the brightest offensive coaching mind in the game. The scary thing for San Francisco's rivals is that the Niners have the financial capital to improve. Such capital can quickly vanish when second contracts come on the horizon, so, though the 49ers will not be expected to go deep into the playoffs this year, a daunting clash with the Vikings marks the opening of a window they cannot afford to waste.

All salary cap figures from Spotrac unless otherwise stated