Jayson Tatum scored 34 points, and Marcus Smart found his groove from downtown in the fourth quarter, as the Boston Celtics rallied from 12 points down in the second half to beat the Toronto Raptors 102-99 Tuesday (US time) to take a 2-0 lead in their Eastern Conference semifinals series.

A free throw by Pascal Siakam capped an 11-0 run to give the Raptors a 78-66 lead late in the third quarter.

But Smart caught fire in the fourth, burying five 3-pointers and scoring 16 of his 19 points in the quarter to put Toronto back on its heels.

Then Kemba Walker, who had struggled in the first three quarters from the field, scored four straight points that launched a 9-0 run to put Boston up 95-87 with 4:18 on the clock.

Toronto made one more push to come to within 100-99 on two Kyle Lowry free throws, but Walker hit a jumper to give the Celtics some breathing space 102-99 with 41.6 seconds remaining.

The Celtics then thwarted the Raptors in the ensuing play when Smart denied Siakam on the drive, forcing a turnover to secure the win.