Larry Bird did it once.
Bill Russell did it twice.
KG did it once last year and is on the verge of doing it again this year.
Other than that, no Celtics team has ever started the season 18-2 or better after 20 games.
I remember being crushed when the Celtics lost at home to the Portland Trailblazers in December of 1985. Not because they lost or because they lost at home. But because the loss dropped the Celtics to 17-3. The Celtics never had a chance to play in the rarefied air of .900 again that season.
Bird and the Celtics had reached .900 during the previous year, starting the 1984-85 season at 18-2. Bill Russell's Celtics also started the 1957-58 season 18-2. However, both Bird's and Russell's fast-starting teams finished the seasons without a ring.
Russell repeated the 18-2 start during the 1963-64 season. This time, however, the Boston Celtics walked home with the championship trophy at the end of the year. KG and the Celtics started last season 18-2, and then reached the .900 plateau again after 30 games, posting a 27-3 record (they went on to win 2 more games before losing three of four).
Now here are KG and the boys threatening to make it two straight years. Motivation certainly hasn't been a problem, with the Lakers a game ahead of them and the Cavs a game behind.
I don't see the Celtics continuing to keep pace with last year. They will stumble eventually. Meanwhile, the Lakers, who were beating up on everyone in the West last year before they got Gasol, are likely to keep rolling, barring injury.
Winning more games than the Lakers isn't crucial. Continuing to beat them in head-to-head match-ups is.
So enjoy the run while it lasts.