SAN ANTONIO -- After back-to-back losses to the New Orleans Pelicans on the road and to the Dallas Mavericks at home, the San Antonio Spurs knows they need to get back to playing the fundamental defense that has made them one of the NBA's elite teams.

That task won't be easy Tuesday when the Oklahoma City Thunder and dynamic point guard Russell Westbrook visit the AT&T Center in San Antonio.

The Spurs and Thunder will meet for the first time this season. The last time the teams faced off was in the 2016 playoffs, where the Thunder beat San Antonio twice in the Alamo City to capture a Western Conference semifinal series.

San Antonio (36-11) have lost back-to-back games for the first time since falling to the Los Angeles Clippers on Nov. 5 and to the Houston Rockets on Nov. 9. The 105-101 setback to Dallas on Sunday was San Antonio's sixth loss to a team with a sub-.500 record. The Spurs have lost only five times to opponents with winning records.

"Our defense was pretty poor -- we were always late on the switches and we were not as attentive as in previous games," Spurs veteran guard Manu Ginobili said against the Mavericks game. "We were a little flat in the third quarter -- it's exactly the same thing that happened in New Orleans (a 119-103 loss on Friday). We have to figure it out."

And they also must worry about stopping Westbrook, who leads Oklahoma City with 30.8 points, 10.8 rebounds and 10.2 assists per game. Westbrook is trying to become the first player since Oscar Robertson to average a triple-double over an entire season.

"He's a great player, and we have try our best to limit his touches and his catches and looks," said San Antonio guard Danny Green, who likely will get the defensive assignment on Tuesday. "We need to try to make one of their other players beat us."

Oklahoma City (28-20) heads into San Antonio off a 107-91 loss at Cleveland on Sunday, when Westbrook had 20 points, 12 rebounds and 10 assists for his 24th triple-double of the season. However, he shot just 7 of 26 from the floor and committed four turnovers.

The Thunder missed their first 12 3-point attempts, shot 6 of 25 from long range in the defeat and made just 37 percent overall from the floor.

"We missed some (layups) around the basket that could have helped us out a little bit," Westbrook said. "Early in the game, it's key that we make those, especially on the road. You've got to be able to make easy baskets."

The Thunder were obviously affected by the absence of reserve forward Enes Kanter, who could miss two months after breaking his right forearm by punching a chair during a timeout in a win over Dallas on Friday.

"(Kanter) generated offense himself by low-post scoring," Thunder coach Billy Donovan said. "He could make a jump shot. He created floor spacing sometimes where we could have him shoot threes. As time goes on, we'll find out more about our team and different things we need to do."