The only concern for the four-time champion is the NBA's best team in the regular season getting a tougher-than-expected series win Sunday at home.
''It doesn't matter how many games it takes,'' Duncan said after the Spurs' 113-111 loss in Dallas on Friday night. ''We're not worried or disappointed.''
San Antonio is going the distance in a second straight playoff series after losing Game 7 of the NBA Finals in Miami last June. The Spurs had an even better chance to close out their fifth title in Game 6, giving up a late lead on a 3-pointer by Ray Allen and losing in overtime. Another good chance slipped away late in the deciding game.
Here they are again, but facing the prospect of losing as the top seed in the West after a 60-win season for the second time in four years. Memphis pulled the trick in 2011, the year the Mavericks won the franchise's first championship.
The winner Sunday gets fifth-seeded Portland in the Western Conference semifinals. The Trail Blazers prevented another possible all-Texas series by ousting Houston on a 3-pointer at the buzzer by Damian Lillard a couple of hours after the Dallas win.
''It's, of course, disappointing,'' said Manu Ginobili, held to six points on 1-of-8 shooting after leading the Spurs in scoring through the first five games. ''But it is what it is. We've got to go fight and try to get it in Game 7.''
Dirk Nowitzki and San Antonio's Big Three of Duncan, Ginobili and Tony Parker were all there eight years ago when these frequent playoff foes played an epic seven-game set in the third of six series between them since 2001.
The Spurs forced a Game 7 in San Antonio after trailing 3-1, then came back from 20 points down in the finale. Ginobili had a tiebreaking 3-pointer in the closing seconds, but Nowitzki had enough time to drive, get fouled by Ginobili on a layup and force overtime with a three-point play. The Mavericks pulled away in the extra period to win the second-round series en route to their first NBA Finals before losing to Miami.
San Antonio was the top seed in the West back then, too. But Dallas was the second-best team in the conference despite being the fourth seed. This time, the Mavericks had to scramble to even make the playoffs a year after missing the postseason for the first time since the 35-year-old Nowitzki's second season in 2000.
''It's another one-game season for us,'' said Dallas coach Rick Carlisle, who had to incorporate nine newcomers, including a revamped backcourt with starters Monta Ellis and Jose Calderon, not to mention Devin Harris at midseason after he came back from toe surgery. ''We've had them all year. We know what they're about, and we wanted this opportunity.''
Ellis scored 29 points in each of the last two Dallas wins and had a huge fourth quarter to hand the Spurs their first road loss of the season when leading after three. Nowitzki carried Dallas through the first three quarters with 18 of his 22.
DeJuan Blair had his second straight double-double - a streak interrupted by his suspension for kicking Tiago Splitter in the head in Game 4. He had to watch his new team play his old team in Game 5 alone in his hotel room in San Antonio.
Blair's reprieve comes Sunday, when the Mavericks go for their first playoff series win since beating the Heat for the title three years ago.
''It's tough to miss a regular-season game. To miss a playoff game is a killer,'' said Nowitzki, who is 4-0 and has averaged 28 points and 15 rebounds in Game 7s. ''Know how bad he felt about missing that one and watching that one in San Antonio. I'm sure he thought to himself he could have helped us out there.''
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