Jeff Zillgitt

USA TODAY Sports

What once looked like a painless stroll through the regular season to the top seed in the Eastern Conference is now more challenging for the defending NBA champion Cleveland Cavaliers.

Before this week, the Cavs’ biggest opponents through mid-April were boredom and complacency.

But Chris Andersen is out for the season, J.R. Smith will miss 12-14 weeks recovering from a broken right thumb (shooting hand) suffered Tuesday against the Milwaukee Bucks and Mo Williams is out for an extended time recovering from knee surgery.

For at least the next two months, the Cavs have 12 active players. That might not be a problem short term — the Cavs beat the Bucks on a back-to-back without Kevin Love for both games and without Smith for six quarters. Andersen wasn’t playing much, and Williams has been inactive all season.

But long term, the lack of bodies could take its toll, and that’s the concern for the Cavs.

Holding off the Toronto Raptors, who are 1 1/2 games behind for the top spot in the East, just got more difficult. The Cavs don’t want a situation where they drop further than a 2 seed. Winning one series on the road is one thing. Winning three series on the road is another.

Such is the backdrop for the Cavaliers-Golden State Warriors matchup on Christmas, one that is much-anticipated, considering it’s the first meeting between the two teams since Game 7 of last season’s NBA Finals when the Cavs completed a 3-1 series comeback with a 93-89 victory in Oakland.

Fans are interested and TV ratings should be strong, but the result is meaningless when it comes to drawing sweeping conclusions about which team will win this season’s championship. Just as Golden State’s Christmas win against Cleveland last season was not a harbinger.

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There are no absolutes in a December game between two of the league’s best teams. If anything, it will give Cavs general manager David Griffin a chance to see what he has — or more important, what he doesn’t have — as he makes plans before the February trade deadline.

The Williams situation is an albatross for the Cavs. The team thought he was going to retire before the season but he didn’t, instead using his player option to stay. He had surgery in October and is taking a needed roster spot.

Why not just eat Williams’ salary and add a player? The Cavs are over the luxury tax and are expected to have another luxury tax bill to pay after this season — about $30 million right now — after paying $54 million last summer. Waiving Williams and adding a minimum salary guy would result in a $13 million payment in salaries and luxury tax.

But the Cavs have options. They can make a deal before the trade deadline, and they also have a $9.6 million trade exception to use. Depending on who that player is if they use the trade exception, it would add salary and increase the luxury tax payment. But for the right player, who can help win another championship, the Cavs are willing to make that deal.

What do they need? A backup point guard or a perimeter player who can generate offense and a perimeter defender. The Cavs need offensive help when LeBron James and Kyrie Irving are not in the game, but they are 15th in defensive efficiency (104.5 points per 100 possessions).

The point guard/offensive player is a need now but won’t be as big of a factor come playoff time when rotations shrink and James and Irving play more minutes. A wing defender will be more important in April, May and June.

Griffin has done a fantastic job creating a roster around stars James, Irving and Love. He acquired Love, Smith, Iman Shumpert, Timofey Mozgov, Channing Frye and Mike Dunleavy during the last two years, and he has made tremendous use of trade exceptions.

Before any deals are made, guards DeAndre Liggins, Jordan McRae and even rookie Kay Felder at times will play valuable minutes, and that will help their development and create more depth.

The front office will do its job, and Cavs coach Tyronn Lue and the players will do theirs.

“Every single game, every single week, just continue to keep getting better,” Lue said.

“For us defensively, we took that challenge the last six or seven games of trying to be more defensive-minded and have a defensive mind-set.

“So for me, just continue to get better and continue to get better at what we’re good at and continue to work on the things we need to get better at, and we got a long season ahead of us.”

Follow Jeff Zillgitt on Twitter @JeffZillgitt