Phoenix ? Steve Nash added the most impressive night yet to his marvelous MVP season, leading the Phoenix Suns within one victory of the Western Conference finals.

Nash had 34 points, 13 rebounds and 12 assists — his third career triple-double and first in the playoffs — and the Suns turned on the jets in a fourth-quarter outburst Wednesday night to beat the Dallas Mavericks, 114-108.

Phoenix took a 3-2 lead in the best-of-seven conference semifinal series, with Game 6 on Friday night in Dallas. Historically, when it’s a 2-all tie, the victor in Game 5 has gone on to win the series 84 percent of the time.

Jim Jackson, the 13-year NBA veteran moved into the starting lineup for the injured Joe Johnson, made seven of eight shots in the fourth quarter for 15 of his 21 points. Amare Stoudemire rebounded from his 15-point performance in Game 4 with 33 points and a career-playoff high 18 rebounds — 21 points and 12 rebounds in the second half. Shawn Marion added 16 points and 10 rebounds for the Suns.

Dirk Nowitzki had 34 points and 10 rebounds for the Mavericks, who led 55-48 at the half. Jerry Stackhouse scored 29 points off the bench. Josh Howard had 19 points and 10 rebounds, and Jason Terry scored 17 points.

But no one on the Mavericks could match the energy and effectiveness of Nash, who came off a 48-point, but losing, effort in Game 4. This time, he scored — and did a lot of everything else, too.

“Obviously, Nash still hurt us in the first half, but he was a monster in the second half,” Dallas coach Avery Johnson said. “We came into tonight’s game trying to cut off some of his passing angles. We did not follow the game plan, and they just shredded us, shredded us to pieces.”