The Green Bay Packers enter their playoff matchup with the Giants as not quite the team that lapped the field to start the NFL season. (Bill Kostroun/Associated Press)

There were times this season when the Green Bay Packers seemed to have lapped the rest of the NFL field. They were chasing an unbeaten season. They had, at one point, three fewer losses than any other team in the league. Aaron Rodgers was crafting arguably the greatest season ever by a quarterback, and a second straight Super Bowl triumph appeared almost inevitable.

But then the Packers lost to the lowly Kansas City Chiefs. Their defense continued its season-long struggles and the offense suffered several key injuries. New Orleans’s Drew Brees moved into the quarterbacking spotlight with Rodgers.

As the Packers, coming off a first-round postseason bye, prepare to host the New York Giants in a division round playoff game Sunday at Lambeau Field, their supremacy over the rest of the field is not what it once was.

“I don’t think they’re overwhelming favorites,” former Packers wide receiver Antonio Freeman said this week. “When I look at the New York Giants, I see a team that’s getting hot at the right time. That’s what carried the Packers through the playoffs last year. The Giants scare me if I’m the Packers.”

Indeed, the Giants are playing their best when it counts, with victories over the New York Jets and Dallas Cowboys at the end of the regular season to capture the NFC East title and a convincing triumph at home over the Atlanta Falcons in their first-round playoff game Sunday. With two 13-win teams, Brees’s Saints and the San Francisco 49ers, squaring off in the other conference semifinal, the NFC playoffs have a more wide-open feel to them than one might expect in a season when the reigning champ went 15-1.

“The 49ers have [tailback] Frank Gore, who can run the ball and control the clock and keep Aaron Rodgers off the field in a [potential NFC] championship game,” Freeman said. “That San Francisco team is one of the top defensive teams in the league. . . . Then when it comes to the Saints, I think the Packers look in the mirror and see the Saints. They’re the same type of offensive team. All three of these teams pose an equal threat to the Packers, to me.”

When the Packers reached 13-0 with a 46-16 victory over the Oakland Raiders on Dec. 11, talk of an undefeated season was building. Every other NFL team had at least three defeats.

But then came the stunner, a 19-14 loss Dec. 18 at Kansas City to a Chiefs team that entered the game with a 5-8 record and had just fired Coach Todd Haley.

The Packers’ imperfections came under scrutiny and the debate shifted to whether their flaws are serious enough to keep them from repeating. They ranked last in the league in pass defense and total defense during the regular season. Rodgers, whose passer rating of 122.5 set a single-season NFL record, played well enough to keep that from mattering. But the offense was short-handed in the season’s late stages because of injuries.

Left tackle Chad Clifton missed 10 games because of hamstring and back injuries before returning in the regular season finale. Right tackle Bryan Bulaga missed the final two games of the regular season because of a knee injury. Wide receiver Greg Jennings was sidelined for the last three games with a knee injury.

All three are scheduled to be in the lineup this weekend against the Giants. Packers Coach Mike McCarthy said at a news conference Monday, “We’re very healthy right now.”

Still, the Packers must rev back up for the playoffs. Their season-opening starters on the offensive line haven’t played together since the third week of the regular season. Rodgers sat out the regular season finale with the top playoff seed already secured, so he’ll be playing on the heels of a three-week layoff. It’s a much different course from the path the Packers followed to the Super Bowl title last season, when they were the NFC’s sixth seed and beat the conference’s top three seeds on the road.

“They’re rested,” Giants defensive end Justin Tuck said after the win over the Falcons. “They’re the number one seed for a reason. They have so much talent throughout their entire football team. The challenge is great. But I feel we’ll be up for it.”

The Giants won the NFC title game in Green Bay in overtime en route to their Super Bowl triumph after the 2007 season. They also pushed the Packers to the limit this season before losing, 38-35, on Dec. 4 at the Meadowlands. The Giants tied that game in the final minute before Rodgers calmly directed Green Bay to a winning field goal as time expired.

“We know offensively we’re going to have to play strong,” Giants quarterback Eli Manning said after the Atlanta game. “We’re going to have to play good. We’re going to have to go score some points. We can’t make mistakes.”

Giants defensive end Jason Pierre-Paul even predicted after the Falcons game that Giants would win in Green Bay. McCarthy said Monday that the game would be “an excellent challenge for us.”

Freeman believes the key could be how Rodgers’s blockers handle a Giants pass rush led by defensive linemen Pierre-Paul, Tuck and Osi Umenyiora.

“When you’re talking about lining up those defensive ends against this beaten-up offensive line, those guys can get around the edges on the Packers and shrink the pocket for Aaron Rodgers,” Freeman said. “. . . I just look at this game as a coin toss, and the Packers are going to need to be on their ‘A’ game to protect Aaron Rodgers.”