By Matthew Geagan, CBS Boston

BOSTON (CBS) — The Boston Celtics had their best win of the season on Monday night, an absolute trouncing of the Los Angeles Lakers. With their starting five intact, the Celtics dropped 137 points on the third-ranked defense in the NBA.

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To say the win was impressive would undersell it quite a bit. The Celtics played with a purpose and a hunger that we haven’t really seen since Christmas Day in Toronto. They were on a mission to prove that they could run with the top teams in the league, and the outcome was a nice reminder of what the Celtics look like when they play up to their ceiling. That was something they had not done for weeks ahead of L.A.’s arrival in Boston.

The Celtics have to be feeling great after Monday’s win, and they should. Embarrassing LeBron James and one of the best teams in basketball has earned them a little bit of clout. But they can’t let that cloud their approach to Wednesday night’s game against the Memphis Grizzlies. Beating the beans out of the Lakers won’t mean as much if the Celtics follow it up with a stinker against the Grizzlies.

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This goes far beyond the fact that the Celtics own Memphis’ first-round pick, which will only convey this year if the Grizzlies fall out of the top-six picks in the draft. With Memphis currently sitting as the eight-seed in the Western Conference at an impressive 20-23, it’s looking more probable than not that the Celtics will be receiving Memphis’ selection.

The 20 wins by Memphis are more than most projected them to win all season. But Ja Morant is leaping out of every gym he visits and is off to a scorching start to his NBA career, averaging 17.9 points and 7 assists. He has a devastating floater and incredible handles, and with Jaren Jackson Jr. continuing to develop at a steady pace, the Grizzlies have a bright future.

They’ve also looked pretty good in the present, going 14-7 since Dec. 7. They’ve scored less than 110 points just once in that span, and have impressive wins over the Rockets and Clippers in the last three weeks. They’re the exact kind of team that the Celtics cannot take lightly, but have overlooked as of late. Wednesday night’s game cannot enter the ranks of recent home losses to the 19-win Spurs, 18-win Suns and 16-win Pistons.

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Monday’s win over the Lakers reminded us just how good the Celtics can be this season. Following it up with anything but a win over Memphis would be a grizzly disappointment, a reminder that they far too often play down to their opposition. With the Celtics stuck in the muddy middle of the Eastern Conference, with five teams separated by just 2.5 games for the No. 2 seed, it’s the kind of setback the Celtics cannot afford.