Brandon Roy scored 18 of his 24 points in the fourth quarter as the Portland Trail Blazers made an improbable comeback from 23 points down for an 84-82 victory over the visiting Dallas Mavericks in Game 4 of their Western Conference first-round series Saturday.

The win evened the best-of-seven set at two games apiece. Game 5 is Monday in Dallas.

After storming all the way back in the fourth quarter, Roy's 21-footer made it a two-point game. Shawn Marion answered for Dallas before Roy buried a 3-pointer as he was fouled by Marion, and made the ensuing free throw to tie the score.

Roy then gave Portland its first lead since the first quarter with a nine-foot bank shot with 39 seconds left.

The Mavericks took advantage of poor shooting by Portland in the first half, and increased their lead to 64-41 before Portland closed to within 18 after three quarters.

Dirk Nowitzki scored 20 points while Jason Terry added 13 and Marion had 12 points and 11 rebounds.

LaMarcus Aldridge finished with 18 points on 6-for-16 shooting for the Blazers. Andre Miller added 14 points while Gerald Wallace had 10 points and 11 rebounds.