The N.B.A. brings out its stars on Christmas. This year, there will be some new rivalries, too.The N.B.A. showcases its stars on Christmas Day, and this year there will be some big names to watch, like LeBron James, Jayson Tatum and Joel Embiid.There will also be a new face in the mix (Memphis Grizzlies guard Ja Morant is playing on the holiday for the first time) and a familiar one missing (Golden State’s Stephen Curry is out injured).In each of the five games, there is something to look forward to, from young players trying to make their mark to older foes avenging playoff losses.Here’s what you need to know.All times are Eastern, and all games will air on ABC and ESPN. The statistics were current entering Friday night’s games.Philadelphia 76ers at Knicks, noonJames Harden missed several games for the Sixers with an injury, but he’s back and helping them stack up wins.Matt Slocum/Associated PressAfter rocky starts, these teams are finally clicking. The Knicks surged up the Eastern Conference standings on the strength of a recent winning streak, while Philadelphia was compiling a streak of its own.They met on Nov. 4, with the Knicks winning, but Philadelphia didn’t have its two best players: center Joel Embiid and guard James Harden. That makes Sunday’s game the teams’ first true matchup. The Knicks have played on Christmas more often than any other team, but this is the first time they will have Jalen Brunson, their big free-agent signing of the off-season.Brunson, a guard who spent his first four seasons in Dallas, leads the Knicks in assists and is the team’s second-best scorer, behind forward Julius Randle. For the first quarter of the season, the Knicks struggled to string together wins. But then December hit, and they found their stride.That’s when fortunes improved for the Sixers, too. Harden had missed more than a dozen games with a foot injury but returned this month to produce several impressive games with double-digit assist totals. The Knicks will, of course, have to watch out for Embiid as well. Last month, in a game against the Utah Jazz, he had this wild stat line: 59 points, 11 rebounds, 8 assists and 7 blocks.Los Angeles Lakers at Dallas Mavericks, 2:30 p.m.Dallas Mavericks guard Luka Doncic is in his fifth N.B.A. season but has already been named to the All-Star team three times.Emil Lippe/Associated PressFans can seemingly always count on seeing the Lakers on Christmas — this is the 24th year in a row — but nothing else about the team has been that consistent.Even as LeBron James, who will turn 38 on Friday, continues to defy reason with his youthful play, minor injuries keep tugging him to the bench. Then there’s the major injury to center Anthony Davis, who is out indefinitely with a sore right foot. Other ailments have rippled through the roster, and the Lakers’ sub-.500 record reflects that. But it also reflects an aging team that got off to a terrible start (0-5) and hasn’t settled into a high-performing rhythm since then.All of that is to say: The Lakers have been a little bit all over the place.Dallas has been, too. Luka Doncic is playing and scoring more than last season, but the Mavericks are losing to bad teams right after beating good ones. The Lakers could fall into either category on Sunday. At the very least, it should be a fun game, with Doncic and James battling to see who can put on the best show. They are both capable of making even the earliest risers hold off on a midday nap.Milwaukee Bucks at Boston Celtics, 5 p.m.Jayson Tatum led the Celtics to the N.B.A. finals last season and has followed that up with high-scoring play this season.David Butler II/USA Today Sports, via ReutersBoston’s Jayson Tatum has responded to his disappointing appearance in the N.B.A. finals last season in the best way: by playing better than ever before. He’s leading the league in minutes per game (37.2), and he’s putting them to good use, averaging a career-best 30.6 points per game by making about half of his shots.The Celtics will face a Bucks team with a not-so-shabby star of its own in Giannis Antetokounmpo. Last season ended in playoff disappointment for him, too, with Milwaukee falling to Boston in seven games in the second round of the Eastern Conference playoffs. Sunday will be his first chance for a little revenge.The Bucks and the Celtics are jockeying for first place in the East, though they are fighting with different strengths. Boston has the league’s second-best offense, while Milwaukee has the third-best defense. The postseason is still a ways off, but it would be a surprise not to see one of these teams in the N.B.A. finals. Their Christmas matchup should help each team see what it needs to work on to make sure it’s the one playing for a title.Memphis Grizzlies at Golden State, 8 p.m.Ja Morant has made the Grizzlies one of the most exciting teams to watch in recent years. Brandon Dill/Associated PressNo one can argue that the Grizzlies haven’t earned this, their Christmas debut.Point guard Ja Morant is the speedy, soaring, confident heart of the team, but Memphis is more than its brightest star — and Morant would be the first to say so. He’s averaging a career-best 7.8 assists per game as he and his teammates keep the Grizzlies near the top of a tightly contested Western Conference.They finished last season as the No. 2 seed in the West and could have made a run to the conference finals if Golden State (and injuries) hadn’t gotten in their way in the second round. Sunday will be the teams’ first meeting since then.Both teams have dealt with their share of injuries this season, but Golden State has an especially big one: Stephen Curry has been out since he hurt his shoulder against Indiana on Dec. 14, and it’s not clear when he will return.Golden State is currently ranked in the bottom half of the West, but the intensity of last season’s playoff series with Memphis should carry over and make Sunday’s game a good contest nonetheless.Phoenix Suns at Denver Nuggets, 10:30 p.m.Denver’s Nikola Jokic won the Most Valuable Player Award the past two seasons.Kevin C. Cox/Getty ImagesThe last game on a long day of basketball is easy to overlook. But Denver’s Nikola Jokic is sure to make at least one pass that will make staying up late worth it. That’s kind of his thing: One minute he has the ball, and then the next his teammate on the other side of the court does, and no one is quite sure how it happened. The Suns are a top-10 defensive team, but some things just can’t be stopped.Phoenix is also the league’s best on offense, which could be a challenge for the Nuggets, who are among the N.B.A.’s worst on defense. Suns guard Chris Paul is one of the best ever at getting the ball to his teammates. Paul led the league in assists last season, his fifth time doing so, and is averaging about nine per game this season.If this game’s late start isn’t a deal-breaker, it should be a nice chance to see some excellent passing and skilled shooters making good on the assist. More
