?Portland Trail Blazers forward Gerald Wallace (L) passes to teammate LaMarcus Aldridge (R, front) as Dallas Mavericks center Brendan Haywood (R) defends during the second half of Game 4 of their NBA Western Conference first round playoff series in Portland, Oregon April 23, 2011. Trail Blazers won 84-82.(Xinhua/Reuters Photo)

The Portland Trail Blazers, led by Brandon Roy, overcame a 23-point deficit to stun the Dallas Mavericks 84-82, while late rallies by the San Antonio Spurs, Chicago Bulls and Denver Nuggets fell short.

Roy scored 18 of his 24 points in the fourth quarter, including the game-winning basket with 39.2 seconds left, thrilling the fans at the Rose Garden in Portland, Oregon, and leveling the best-of-seven series at two home wins each.

The Trail Blazers survived two missed 3-point attempts by the Mavericks in the closing seconds.

"It still doesn't feel real yet. Just an unbelievable game, the comeback," said Roy who underwent arthroscopic surgery on both knees in mid-January. "With everything I've been through this season, it all came into that moment there on the court, when guys were grabbing me and cheering me on. It was real special."

LaMarcus Aldridge scored 18 points for Portland and Gerald Wallace recorded a double-double with 10 points and 11 rebounds. Dirk Nowitzki led the Mavericks with 20 points.

In Memphis, Tennessee, the eighth seeded Grizzlies hung on for a 91-88 win over the Spurs to grab a 2-1 lead over the Western Conference's top seeds.

The Grizzlies seized control of the game early with a 14-4 surge spanning the first and second quarter, but needed a rare 3-point basket from Zach Randolph with 41.9 seconds to secure the victory.

Randolph led the Grizzlies with 25 points while the Spurs were led by Manu Ginobili's 23 points.

In Indianapolis, the Chicago Bulls blitzed the Pacers in the final four minutes but were unable to complete the comeback falling 84-89.

Chicago outscored Indiana 18-3 over a 3:30 span to move to within one point at 85-84 with 15.3 seconds but Danny Granger, who led the Pacers with 24 points, hit two critical free throws extending the Pacers lead back to three points.

Chicago's Carlos Boozer missed on a clear 3-point attempt on a broken play with three seconds remaining and Granger hit two more free throws to finish the game.

Joakim Noah led Chicago with 21 points and 14 rebounds and Rose scored 15 points and had 10 assists.

In the late game, the Oklahoma City Thunder rebounded from a dismal third quarter for a 97-94 win over the Denver Nuggets to take a commanding 3-0 series lead.

The Nuggets outscored Oklahoma City 24-15 in the third quarter to take a 73-71 lead into the fourth quarter. Russell Westbrook led the Thunder to victory in the fourth quarter with 13 of his 23 points.

Kevin Durant led the Thunder with 26 points and Kenyon Martin, Nene, and JR Smith scored 15 points each for Denver.