Paul Pierce Says Celtics In 6, 'Stop Playin''

Paul Pierce says he ain't worried about the Celtics being down 2 games to 1 to the Milwaukee Bucks ... telling TMZ Sports his guys will WIN the whole series in 6.

The Truth was leaving Meek Mill's birthday party at 1 OAK in L.A. on Sunday -- when we asked about his Boston Celtics losing 2 games in a row to Giannis Antetokounmpo and company.

Remember, the Celtics started off strong -- with a dominating 112 to 90 victory over the Bucks in Game 1.

But, the last 2 games have been all Milwaukee ... and now Vegas is highly favoring Milwaukee to win the series. The winner of this series will play the winner of the 76ers vs. Raptors series in the next round.

But, Pierce doesn't give a DAMN about the odds -- telling TMZ Sports he expects his guys to rally back and the take the series.

"Celtics in 6, homie. Stop playin'."