Budda Baker was worried.

In late-July, Major League Baseball had a bumpy start to its season as COVID-19 infiltrated the rosters of the Miami Marlins and St. Louis Cardinals, and it was easy to assume the NFL would face similar obstacles.

"If you would have told me a month ago that we were going to be starting on time and playing football," the Pro Bowl safety said, "I wouldn't have probably believed you."

Baker was thrilled to be proven wrong, as impressive dedication to combating the coronavirus – likely spurred by those fears – has kept the NFL season on track.

The leaguewide cases are low, and the Cardinals' first blip didn't arise until Friday, when backup wide receiver KeeSean Johnson was placed on the COVID-19 reserve list.

Kingsbury acknowledged from the start the team would not make it through the season unscathed, but as long as other players weren't infected, it shouldn't have a big effect on Sunday's matchup -- the much-anticipated season opener against the defending NFC champion 49ers.

Despite coming off a five-win season, there has been a steady climb of anticipation heading into the second year of the Kliff Kingsbury and Kyler Murray era.

The Cardinals' biggest hole on offense last season was the absence of a game-breaking receiver, so General Manager Steve Keim traded for DeAndre Hopkins. The defense had stars – Baker, outside linebacker Chandler Jones and cornerback Patrick Peterson – but lacked depth, so Keim got busy in free agency and the draft to fortify the unit.

The Cardinals found a groove down the stretch of 2019, and they have a better roster on paper heading into 2020.

"We think the sky can be the limit for us," Peterson said. "We have a lot of great pieces. We have the core of the team coming back from last year. I really believe those last five games we turned the corner."

Among the Cardinals' longtime veterans, Peterson is the idealist, while Larry Fitzgerald is the pragmatist. The future Hall of Fame receiver wants to first see how the Cardinals handle the road opener against a team that was a couple plays away from winning last year's Super Bowl.

San Francisco lost some key pieces this offseason – most notably defensive lineman DeForest Buckner and wide receiver Emmanuel Sanders – but still has arguably the deepest roster in the conference.

"We haven't been hit in the mouth yet," Fitzgerald said. "We haven't faced any adversity at all. On Sunday we'll face our first bit of adversity. They're going to make plays, they're going to knock passes down. They're going to do stuff. They're a really daggone good football team. We're going to find out a lot about our resolve and our fight and what we're really made of this Sunday, playing against an elite, elite team that is pretty much doing what we're trying to do – get to the Super Bowl."

The Cardinals had two of their finest games of 2019 against the 49ers. In the first, an 88-yard Andy Isabella touchdown cut a late deficit to three points, but San Francisco then ran out the clock.

In the second, the Cardinals led 16-0 in San Francisco and had the ball with a three-point lead late in the fourth quarter before squandering it.

"We played them good twice or whatever, but we still lost twice, so that's a fail on our part," Murray said.

Like every other team, the Cardinals dealt with no offseason work and a truncated training camp. Despite those obstacles, Kingsbury has been pleased with his team's progress, and knows the 49ers will be a great litmus test.

"We'll definitely find out where we're at in a hurry," Kingsbury said.

In true 2020 fashion, multiple wildfires near the Bay Area are threatening to disrupt the game, as they have turned the sky orange and made the air quality poor. If the air quality index rises above 200, San Francisco coach Kyle Shanahan said the game would not be allowed.

After handling COVID-19 well, the Cardinals hope that's not the case.

"We can roll the ball out in a parking lot somewhere," Peterson said. "We just want to have our opportunity to play a football game Sunday."