If you want to be the best, you've got to beat the best, and that's exactly what the Boston Celtics did.
The league's leading defense held the defending champion Golden State Warriors to a season-low 88 points Thursday night to keep its winning streak alive, and added a 15th consecutive win Saturday against the Atlanta Hawks.
The run vaults Kyrie Irving & Co. to the No. 1 spot this week ahead of Golden State and Houston, which has won two in a row in dominant fashion following the return of Chris Paul.
Every Monday throughout the regular season, our panel -- ESPN's Kevin Arnovitz, Amin Elhassan and Ramona Shelburne, The Undefeated's Marc J. Spears and FiveThirtyEight's Chris Herring -- will rank the league's 30 teams from top to bottom, with research notes on each team provided by ESPN Stats & Information.
Previous rankings: Week 5 | Week 4 | Week 3 | Week 2 | Week 1
1. Boston Celtics
2017-18 record: 15-2
The Celtics have won 15 straight games and have done it with defense. During the streak, they've allowed All-Stars from last season to combine for a 14.7 player efficiency rating, which is worse than the average NBA player (15.0). Perhaps even more remarkable: Saturday was the first of eight straight games in which the Celtics don't face any All-Star from last season, the second-longest stretch by any team this season. Boston has a chance to keep its run rolling. -- Vincent Johnson
2. Golden State Warriors
2017-18 record: 13-4
The Warriors and Thunder square off for the first time this season on Wednesday (8 p.m. ET on ESPN). The Warriors won all four matchups last season by an average of 19.8 points per game, their second-largest differential against any opponent they faced four times. For the Thunder, it was their worst points per game differential against any team. -- Jose De Leon
3. Houston Rockets
2017-18 record: 13-4
The Rockets have won each of their past five road games by 15 points or more, tied for the longest streak in NBA history. The previous three teams to do that each won the NBA title: 2011-12 Heat, 2003-04 Pistons, 1969-70 Knicks. Over the past two weeks, James Harden had a six-game stretch where he averaged 40 points and 10 assists, the third player ever to put together a stretch of that kind, joining Tiny Archibald and Oscar Robertson. -- Vincent Johnson
4. San Antonio Spurs
2017-18 record: 10-6
The Spurs overcame a 23-point deficit to beat the Thunder on Friday. It's the franchise's fourth-largest comeback win under Gregg Popovich, including the playoffs. -- Jose De Leon
5. Toronto Raptors
2017-18 record: 11-5
During their season-high four-game win streak, the Raptors have posted an NBA-best 118.1 offensive efficiency. In those four wins, Toronto has outscored its opponents by nearly 16 points per 100 possessions while shooting 53 percent from the floor. -- Jose De Leon
6. Minnesota Timberwolves
2017-18 record: 10-6
In the loss against the Pistons on Sunday, Jimmy Butler joined Kevin Garnett and Tom Gugliotta to become the third player in Timberwolves history with at least 25 points, 10 rebounds and five steals in a game. -- ESPN Stats & Information
7. Detroit Pistons
2017-18 record: 11-5
The Pistons trailed by as many as 11 points in their win over the Timberwolves on Sunday. It was Detroit's league-leading sixth win after trailing by double digits this season. -- Jose De Leon
8. Cleveland Cavaliers
2017-18 record: 9-7
The Cavaliers' word of the week last week: resilient. They came back to beat the Knicks after trailing by 23 points and beat the Clippers after trailing by 15. Cleveland had lost its first six games of the season when trailing by at least 15 points. -- Jose De Leon
9. Denver Nuggets
2017-18 record: 9-7
Jamal Murray has been a bright spot for the Nuggets this season. He already has two 30-point games after recording one as a rookie last season. -- Jose De Leon
10. Washington Wizards
2017-18 record: 9-7
On Sunday, the Wizards played the front end of their first back-to-back of the season. Last season, the Wizards were 7-9 overall on zero days of rest but have won six of their past eight such games. -- Jose De Leon
11. Portland Trail Blazers
2017-18 record: 9-7
The Trail Blazers are about to begin a five-game road trip. They won their first two games of the season on the road but have since lost three straight; two decided by fewer than five points and the other in overtime. -- Jose De Leon
12. Oklahoma City Thunder
2017-18 record: 7-8
The Thunder continue to struggle down the stretch of games this season and are now 0-7 in games decided by eight points or fewer. But in their wins, OKC has won big, averaging a wider margin than the Warriors (plus-17.9). That's the reason they're the only sub-.500 team with a positive scoring margin this season. -- Vincent Johnson
13. Milwaukee Bucks
2017-18 record: 8-7
Outside shooting has been a concern for the Bucks this season and point guard addition Eric Bledsoe hasn't done much to help address it. He is shooting 19 percent (6-for-31) outside the paint since joining Milwaukee. -- Jose De Leon
14. Philadelphia 76ers
2017-18 record: 8-7
A 47-point first quarter wasn't enough to beat the Warriors on Saturday. Philadelphia's 47 points are its most in any quarter since March 30, 1990, against the Nuggets (also 47 points in the first quarter of that game). -- ESPN Stats & Information
15. Memphis Grizzlies
2017-18 record: 7-8
Mike Conley has missed the past two games and will continue to be out indefinitely with a sore Achilles. That doesn't bode well for the Grizzlies, as they've lost four straight by an average of nearly 12 points per game. -- Jose De Leon
16. New Orleans Pelicans
2017-18 record: 8-8
DeMarcus Cousins is averaging career highs in points per game (27.1), rebounds per game (13.2) and assists per game (5.6). He is on pace to joining Kareem Abdul-Jabbar, Wilt Chamberlain and Elgin Baylor as the only players to average 27-13-5 for a season. -- Jose De Leon
17. Orlando Magic
2017-18 record: 8-8
On Monday, the Magic will look to avoid their fifth straight loss and also will try to avoid falling under .500 for the first time this season. The Magic are one of just seven teams that have not been below .500 this season. -- Jose De Leon
18. New York Knicks
2017-18 record: 8-7
Kristaps Porzingis is in a bit of an efficiency slump, shooting 34 percent from the floor while averaging 18.3 points over his past three games. In his four games prior, Porzingis averaged nearly 35 points per game on 60 percent shooting from the floor. -- Jose De Leon
19. Indiana Pacers
2017-18 record: 9-8
A season-high fourth straight win on Monday against the Magic will put the Pacers two games above .500 for the second time this season. The 3-pointer has been key for the Pacers during their three-game winning streak as they've shot 51 percent from beyond the arc in those games. -- Jose De Leon
20. Utah Jazz
2017-18 record: 7-10
Prior to Rudy Gobert's injury, the Jazz ranked first in the league in opponent points in the paint per game. They're 11th in the league in that department in the five games played without Gobert. That could spell trouble for the Jazz as they face Joel Embiid and the 76ers on Monday: Embiid averages 11.2 points in the paint per game, 10th in the NBA. -- Jose De Leon
21. Miami Heat
2017-18 record: 7-9
On Sunday against the Pacers, Dion Waiters went 0-for-10 from the floor, his most attempts without a make in his career. For what it's worth, Waiters has just the third-most attempts without a make in a game this season. Stanley Johnson went 0-for-13 to open the Pistons' season and Rodney Hood was 0-for-11 against the Trail Blazers on Nov. 1. -- Jose De Leon
22. LA Clippers
2017-18 record: 5-10
The Clippers have followed up a 5-2 start to the season with an eight-game losing streak, their longest since losing nine straight in November 2010. Through their first seven games, the Clippers had the fifth-best defensive efficiency in the league. Over their past eight games, only the Pelicans have a worse defensive efficiency. -- Jose De Leon
23. Charlotte Hornets
2017-18 record: 6-9
Kemba Walker scored 47 points, the second most in his career, in Friday's three-point loss against the Bulls. According to Elias Sports Bureau research, the Hornets have lost 11 straight games decided by three points or fewer, tied for the second-longest streak in the NBA since 1979, when the 3-point line was implemented. -- Jose De Leon
24. Los Angeles Lakers
2017-18 record: 7-10
On Sunday, Lonzo Ball recorded his second triple-double of the season in his 17th game. Only five players needed fewer games to record two career triple-doubles in NBA history: Oscar Robertson (3), Ben Simmons (9), Hambone Williams (10), Magic Johnson (12) and Connie Hawkins (14). -- Micah Adams
25. Brooklyn Nets
2017-18 record: 6-10
Brooklyn cut Golden State's lead to four points with 2:38 left in the game on Sunday, but their bevy of 3-point attempts wasn't enough to completely erase their deficit. The Nets attempted 48 3-pointers in the loss, their most in franchise history. -- ESPN Stats & Information
26. Phoenix Suns
2017-18 record: 7-11
The Suns gave up 90 first-half points to the Rockets in their loss on Thursday. That's tied for the second-most points allowed in a first half in the shot clock era (since 1954-55). -- Jose De Leon
27. Sacramento Kings
2017-18 record: 4-12
On Wednesday (10:30 p.m. ET on ESPN) Lonzo Ball and De'Aaron Fox will square off for the first time as pros and for the first time since the Sweet 16 in March. In that Kentucky victory over UCLA, Fox had 39 points and one turnover; Ball finished with 10 points and four turnovers. -- Jose De Leon
28. Dallas Mavericks
2017-18 record: 3-14
The Mavericks won their third game of the season thanks largely to their defense. They held the Bucks to 79 points -- the fewest points scored by Milwaukee this season and the fewest allowed by Dallas this season -- in the 32-point win. Among teams without a 30-point win this season are the the Celtics, Cavaliers and Rockets. -- Jose De Leon
29. Atlanta Hawks
2017-18 record: 3-13
The Hawks won their third game of the season in dominating fashion. They beat the Kings by 46 points on Wednesday, their largest win in franchise history. -- Vincent Johnson
30. Chicago Bulls
2017-18 record: 3-11
The Bulls have yet to win back-to-back games this season but finally scored 100 points in consecutive games for the first time. They were the only team without 100 points in back-to-back games this season. -- ESPN Stats & Information