The winner will gain the Western Conference's seventh seed, and the visiting Mavericks will be seeking to complete their first season sweep of the Grizzlies in six years.
These Southwest Division rivals have 49-32 records, and Wednesday's loser will be seeded eighth and face San Antonio in the first round. Both clubs lost all four meetings with the league-best Spurs.
"They'll be at home, they're going to try to win their 50th, we want to win 50, everybody wants to move up and get a higher seed if they can," Dallas coach Rick Carlisle said.
Memphis clinched the league's final playoff spot Monday by scoring the final seven points in a 97-91 win at Phoenix. Zach Randolph fed Mike Conley for a go-ahead 3-pointer with 68 seconds left that triggered the final burst.
The Grizzlies have won four straight and are 22-10 since Feb. 9 for the West's third-best mark in that span.
''We've needed every game basically since February it seems like,'' Conley said. ''We've played every game like a playoff game. It's been fun to be part of a group that comes in and stays focused and to get back in the playoffs.''
Memphis can set a single-season record with a 14th straight home win Wednesday.
Dallas is seeking its first seven-game road win streak since winning eight in a row Nov. 20-Dec. 27, 2010. That season marked the Mavericks' 11th straight with at least 50 wins and they can reach that plateau Wednesday for the first time since.
"I think we took 50 wins for granted a little bit there a couple times, when we just did it a few times in a row there, won 67 (in 2006-07), you think 50 wins is easy to get but it's really not," forward Dirk Nowitzki said.
Monta Ellis matched his season high with 37 points and Nowitzki scored 21 of his 23 in the second half Saturday as the Mavs rallied from 13 down for a 101-98 clinching home win over the Suns. The club's 12-year streak in the playoffs ended last season.
Nowitzki is averaging 23.3 points on 57.8 percent shooting in the season series, with Dallas winning by an average of 13.4 points. The Mavs last swept four meetings in 2007-08.
This season's results may be deceiving since Marc Gasol missed one meeting while Conley sat out twice.
The Grizzlies are 39-18 when they start Gasol and Randolph.
"We've got to be ready to guard those guys with a lot of different people, probably a lot of different schemes," Carlisle said. "It's a very challenging game from that perspective. I don't know of another team in the league that has two guys of this magnitude of post-up scoring ability, rebounding ability and they both are playmakers as well from the inside out."
Ellis is tied for third in the NBA with 10.1 drives per game entering play Tuesday. He's averaged 8.3 in the season series against a Grizzlies team that's allowing a West-low 38.5 points per game in the paint.