ESPN

The Dallas Mavericks already got their marquee player back from injury, while the Washington Wizards continue to anxiously await the return of theirs. But both teams continue to struggle heading into Tuesday night's game at Washington.

The Mavericks (12-19) had lost two straight when Dirk Nowitzki made his season debut Dec. 23 against San Antonio, but Dallas has lost all four games since its star forward returned. Nowitzki, who averaged 21.6 points per game in 2011-12 without missing a game, missed the first 27 contests this season after undergoing knee surgery.

The 11-time All-Star is clearly not in top form yet, shooting a career-low 32.4 percent from the field. He hasn't scored more than nine points while playing an average of 21.8 minutes as he tries to improve his conditioning.

Sunday was another struggle, with Nowitzki scoring eight on 3-for-9 shooting in a 111-86 home loss to the Spurs, the Mavericks' sixth straight defeat to mark their longest losing streak since January 6-17, 2011.

Dallas hasn't dropped seven in a row since Feb. 9-19, 1999.

"Obviously Dirk is not ready," Spurs coach Gregg Popovich said. "He's not Dirk Nowitzki, basically one of the greatest players that's ever played, so it's going to take time for him. Everybody's just trying to figure out their place and work around and get back into a rotation. It's very, very difficult when you have a guy like that out and then he comes back."

O.J. Mayo picked up the primary scoring load while Nowitzki was out, averaging a career-best 19.8 ppg. But he's struggled since Nowitzki returned, averaging 8.5 points on 33.3 percent shooting, making his teammate's slow return to form even more noticeable.

Coach Rick Carlisle has regularly shuffled his lineup to try to find answers, but no combinations have kept Dallas from falling seven games under .500 for the first time since April 6, 2000 -- the first season Mark Cuban owned the team. Carlisle used his 14th different starting lineup against the Spurs, giving Vince Carter his first start of the season. Carter finished with 13 points on 5-of-11 shooting.

"We've got to stick together and we've got to fight," Carlisle said. "And we've got to fight harder than we did tonight."

The league-worst Wizards (4-24) have lost nine of their last 10 as they are still without John Wall. The third-year point guard is still limited to non-contact work in practice as he recovers from a patella injury.

Wall's absence isn't helping Washington's league-worst field-goal percentage (40.6 percent). The Wizards turned in their 12th sub-40.0 percent shooting performance in Saturday's 87-77 loss at Chicago as leading scorer Jordan Crawford (16.0 ppg) sat out with an ankle injury. Crawford was a full participant in Monday's practice.

"We just didn't have our offense," coach Randy Wittman said. " ... Tonight we came out and battled hard, even though short-handed. Yes, it hurt to lose our leading scorer but it isn't that reason we lost."

Crawford scored 21 points off the bench in Washington's 107-101 loss at Dallas on Nov. 14 -- the Wizards' fifth straight defeat in the series. Mayo led the Mavericks with 25 points on 9-of-15 shooting.