Oklahoma City ? History can mean everything or nothing.

In the case of Game 3 of a playoff series for the Dallas Mavericks, it has been guaranteed in the past to mean one or the other.

The Mavericks have been tied 1-1 in a best-of-seven playoff series nine times in the Dirk Nowitzki era.

All nine times, the winner of Game 3 has won the series.

Everything. Or nothing.

If history holds, that’s what’s on the line tonight at Oklahoma City Arena.

Live-in-the-moment coaches and players won’t buy into that, of course. Win or lose, there still will be a long way to go in the Western Conference finals.

But there can be no denying that this juncture of a sticky-close playoff series is usually where the momentum cuts in to dance with one side or the other.

The Mavericks need to win Game 3 or they’ll find themselves trailing a playoff series for the first time this postseason. They went up, 2-0, on Portland and the Los Angeles Lakers. The Blazers came back to tie it 2-2, but the Mavericks won the next two games to close it out. The Lakers got swept.

This Oklahoma City team is “a different animal,” as Nowitzki said, referencing to their at-times overwhelming speed and high-octane offense.

“We’ve got to go into this next game like we’re down, 0-2,” Mavericks coach Rick Carlisle said Friday.

What the Mavericks have working in their favor are the facts that they have been an excellent road team throughout the season — particularly so in the playoffs — and that the Thunder will have all the pressure in Games 3 and 4.

The home team always has the pressure to hold serve in a series that is too close to call. And this one certainly is that.

To their credit, the Mavericks have not lost an ounce of confidence. They still feel they are the better team in this series. They still don’t see any reason to change the game plan. As Tyson Chandler said Friday, you have to actually execute the game plan before you can tell whether it stinks or not.

“We’ve got to treat it like it’s a must game,” Chandler said. “Every game from here on out, we’ve got to treat it like we’re in a hole, and it’s a Game 7.

But the Mavericks have not played defense anywhere close to the way they did in the series against the Lakers.

And for the first time since Game 4 against Portland, the Mavericks’ bench was thoroughly beaten Thursday by James Harden, Eric Maynor, Daequan Cook and Nick Collison of the Thunder.

“It’s been a while since we lost, so we’re not going to like this feeling,” Mavs guard Jason Terry said. “It’s obvious that whichever bench is able to make an impact on the game is going to have a better chance to be successful. Give their bench a lot of credit.”

This series is even because both teams have shot extremely well in one game. The Mavericks’ hot shooting in Game 1 masked the fact that their defense was vulnerable. When their shots didn’t drop in Game 2, it was obvious they had defensive problems that need to be fixed, like keeping Thunder players from carving to the basket or taking uncontested jump shots.

“Sometimes, you can talk about things, but until you get smashed in the face, it doesn’t really hit you,” Carlisle said. “You look at 109 points scored on you (on average) in the first two games, the fact we won one of those is a good thing because defensively we have not been good.”