Dallas Mavericks' Dirk Nowitzki of Germany (C) hoists the conference trophy while flanked by team owner Mark Cuban (L) and Jason Kidd after the team defeated the Oklahoma City Thunder in Game 5 of the NBA Western Conference Final basketball playoff in Dallas, Texas, May 25, 2011. [Photo/Agencies]

Oklahoma City Thunder's Kevin Durant (L) and Russell Westbrook react during Game 5 of the NBA Western Conference Final basketball playoff against the Dallas Mavericks in Dallas, Texas, May 25, 2011. [Photo/Agencies]

DALLAS - The Dallas Mavericks overcame an eight-point deficit in the fourth quarter to reach the NBA finals for only the second time with a 100-96 victory over the Oklahoma City Thunder on Wednesday.

Dallas clinched the best-of-seven Western Conference Finals series by a 4-1 margin with the thrilling Game Five win and will face either the Miami Heat or the Chicago Bulls in the NBA finals. The Heat lead that series 3-1.

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Roared on by their home fans, talisman Dirk Nowitzki, who sealed the triumph with a pair of late free throws, and fellow forward Shawn Marion scored 26 points apiece while Jason Terry weighed in with 12 points off the bench.

Guard Russell Westbrook scored a game-high 31 points for the Thunder, who were unable to prevent the Mavericks from conjuring a second successive come-from-behind win. NBA scoring champion Kevin Durant added 23 points for the visitors.

Dallas, who won Game Four 112-105 after overtime in Oklahoma City two days earlier, opened an early six-point lead but the Thunder hit back to lead 27-26 after the first quarter.

The Mavericks twice drew level before the fourth-seeded Thunder edged ahead again to lead 55-53 at halftime.

With James Harden and Nick Collison sparking Oklahoma City's bench, the visitors kept the third seeds under continual pressure to grab a 76-72 advantage going into the final period.

Westbrook landed a two-point jumper to put the Thunder ahead 85-77 for the biggest lead of the night with 9.14 remaining.

However, the Mavericks steadily clawed their way back, and had reduced the deficit to 92-90 with a little under four minutes on the clock following consecutive pairs of free throws from Nowitzki and veteran Marion.

Nowitzki then missed a three-point attempt but Dallas stole the rebound and this time the German made no mistake from beyond the arc to put his team ahead 95-94 with 1.14 left.

The Thunder again lost possession, this time on attack, and Marion burst away to score with a running slam dunk shot, forcing a foul for a bonus free throw to give Dallas a 98-94 lead which they never relinquished.

The Mavericks, who swept the defending champions Los Angeles Lakers in the previous round, reached the NBA finals once before in 2006, when they were beaten 4-2 by the Miami Heat.