Golden State coach Don Nelson, left, talks with Mickael Pietrus during the Warriors' 111-82 victory over the Mavericks on Tuesday in Oakland, Calif. The teams will meet in a first-round playoff game Sunday in Dallas.

Dallas ? Watching from a tunnel as the Dallas Mavericks played in the NBA finals last season, Don Nelson had to feel like a proud father.

In many ways, he was – with his son running the front office, close friends he’d hired coaching the team and guys he’d molded such as Dirk Nowitzki and Josh Howard leading the way on the floor.

Nellie will have an even closer look at the Mavs at the start of this postseason. He’ll be coaching against them.

Now guiding the Golden State Warriors, Nelson’s club snagged the final spot in the Western Conference playoffs on the final day of the season. As luck would have it, their first-round foe is the Mavericks, who are coming off a 67-win season that tied the sixth-most in league history.

So put aside the relationships. Nelson’s goal starting Sunday night in Dallas will be to destroy the monster of a club he created.

“It’s going to be a good old- fashioned family feud,” said Donnie Nelson, the Mavericks’ president of basketball operations and the son of the Warriors’ coach. “I’m sure when Nellie comes down, we’ll get the kids together and hang out and have a good meal. Then the next day we’ll try to rip each other’s throats out.”

Mavericks coach Avery Johnson’s relationship with Don Nelson dates to the 1993-94 season, when they were together in Golden State. Nelson made Johnson a full-time starting point guard for the first time in his career that season and was rewarded with a trip to the playoffs. This is the Warriors’ first time back since then.

Reunited as player and coach in Dallas a few years ago, they later hatched a succession plan. Johnson was to eventually replace Nelson as coach of the Mavericks. Eventually came much sooner than expected, with Johnson taking over in March 2005 after only 64 games. He got Dallas into the NBA finals last year, his first full season in charge.

Because Nelson was around last season as a consultant, he’s still very familiar with the Mavericks. And because he’s still a heck of a coach, Golden State went 3-0 against Dallas this season. The Warriors spoiled the game when the Mavs dropped a banner honoring their Western Conference title and later ended a 17-game winning streak.

So Nellie’s return for the first round is about more than nostalgia. It could be a tough start for the Mavericks in their bid to win the title they lost in heartbreaking fashion last summer.

“I think it’s great for the NBA,” Johnson said. “He and I have had a long history together … (but) the teams are going to decide it.”

Postseason reunions are becoming common for the Mavericks. Two years ago, it was Steve Nash in the second round. Last year, it was Michael Finley in the second round and Nash in the conference finals. So Nowitzki isn’t too worked up about seeing his old coach.

“It’s fine,” he said. “It doesn’t matter who we play against. Every team in the playoffs is good and presents problems. Obviously we know Nellie’s style is up and down, and it’s all about matchup problems.”