Lillard scored 31 points and doled out nine assists and McCollum added 26 points as the Trail Blazers (25-21) won their third straight game and sixth in a row at home.
Wesley Matthews led Dallas (15-31) with 23 points while Dirk Nowitzki and Dennis Smith Jr. each chipped in 21.
Lillard made his first nine shots from the field - seven of them 3-pointers. He finished 10-for-15 from the field and 7-for-9 from 3-point range.
Portland shot .523 from the field, sinking 18 of 36 3-point tries.
Lillard had 18 points at halftime on 6-for-6 shooting, including 4-of-4 on 3-pointers, as Portland mounted a 62-45 halftime lead. McCollum had 13 points and Evan Turner 12 for the Blazers, who shot .571 in the half.
Dallas opened the second half with an 11-2 spurt that closed the gap to 64-56. Matthews buried back-to-back 3s to close the gap to 74-69. Portland responded with a 14-2 run to go ahead 88-71. The Blazers carried a 91-79 lead into the final period.
Smith's 3 cut Portland's advantage to 95-87 with 9:29 remaining. Nowitzki's layup cut it to 100-93, but Shabazz Napier knocked down a trey to make it 103-93 with 6:10 left.
Dallas got to within 107-100 on a pair of J.J. Barea baskets. Turner's jumper made it 109-100 with 3:01 to play.
Matthews scored on a banker to trim the difference to 113-106 with 1:03 to go. Smith scored on a driving layup to close the gap to 113-108 with 47.5 seconds left. Ed Davis' dunk sealed the verdict for Portland with 17.1 ticks on the clock.
Portland sank 4 of 6 attempts from 3-point range in the first four minutes to spring ahead 16-9. The Blazers, with Lillard providing 13 points, extended the difference to 33-20 after one quarter.
The Blazers stoked their edge to 57-39 advantage late in the second quarter. The margin was 17 points at intermission.
--Field Level Media
Dallas | Portland | |
Wesley Matthews 23 | Scoring | Damian Lillard 31 |
J.J. Barea 6 | Assists | Damian Lillard 9 |
Harrison Barnes 10 | Rebounds | Ed Davis 10 |
Wesley Matthews 6 | Free Throws Made | Damian Lillard 4 |
Dennis Smith Jr. 3 | Steals | Al-Farouq Aminu 1 |
Salah Mejri 2 | Blocks | Ed Davis 2 |
Team | Points | FG% | 3PM-3PA | FTM-FTA | Assists | Rebounds | Blocks | Steals | Turnovers |
Dallas | 108 | 45.8 | 10-25 | 22-28 | 19 | 37 | 5 | 9 | 9 |
Portland | 117 | 52.3 | 18-36 | 9-10 | 19 | 40 | 3 | 3 | 14 |