Duncan scored 26 points, Finley added 19, and San Antonio rallied for a 109-100 victory over the Sacramento Kings on Wednesday night.
Duncan scored 13 in the fourth quarter and Finley added 10 to help the Spurs rally from a five-point deficit in the third.
"It was a good fourth quarter," Spurs coach Gregg Popovich said. "Tim [Duncan] was tough in the hole and Michael Finley shot the ball well. It got us through."
With four games remaining, the Spurs (57-21) have a shot at their second consecutive 60-win season and their third in the last five seasons. They have won five straight and 11 of 12.
Though the Dallas Mavericks have clinched the best record in the league, the Spurs are a league-best 22-3 since the All-Star weekend.
Ron Artest sat out with a sore left hamstring for Sacramento, which trailed 54-48 at halftime but outscored San Antonio 15-4 in the opening 4:21 of the third quarter.
Sacramento led by a point heading into the fourth quarter, and was up 86-85 when Shareef Abdur-Rahim scored on a layup with 9:25 remaining in the game.
But that's when Duncan and Finley took over, combining to go 8-for-8 from the floor in the final quarter.
"[Duncan] had an MVP type of performance -- he always does," Kings coach Eric Musselman said. "He did his thing in the fourth quarter, and they pulled away."
The Spurs went ahead 87-86 on Duncan's bank shot with 8:06 remaining in the game. Finley hit a pair of 3-pointers and another outside jumper during the next 3:11 to give the Spurs a 96-89 lead with 4:55 to go.
Finley entered the starting lineup four games ago when Brent Barry began having back spasms.
"I'm just making the most of my opportunity," Finley said. "We have great playmakers, and they just set me up."
The Kings got to within four points when Mike Bibby hit a pair of free throws with 3:35 to go.
But after Finley hit a pair of free throws and Duncan knocked down a bank shot in the lane, the Spurs led 107-96 with 1:35 to go.
They swept the Kings 4-0 in the season series. San Antonio has won a season-best nine straight at home.
Sacramento led 63-58 with 7:39 remaining in the third quarter when Francisco Garcia hit a 3-pointer from the corner. During the Kings' early second-half spurt, Garcia hit three of four shots from the floor, had three rebounds and an assist.
He finished with 22 points. Bibby also had 22, but had five turnovers.
After the Spurs cut the Kings' lead to two when Finley answered Garcia's 3-pointer with his own 3, Garcia came back down the court and knocked down a short jumper to give Sacramento a 65-61 advantage.
Sacramento shot 43 percent from the floor, but the Kings were 10-of-19 from 3-point range.
"Francisco Garcia and Bibby were hitting a lot of threes," said Tony Parker, who added 14 points and eight assists for the Spurs. "It was a hard time for us trying to get a solid lead. In the fourth quarter, we finally made some baskets and made a run and won the game."
It's the sixth game Artest has missed this season due to injury. ... Brad Miller started at center for the Kings and played 9 minutes in the first quarter before sitting out the rest of the game with plantar fasciitis in his left foot. Miller has sat out 14 games this season because of the injury. ... Barry and Robert Horry both returned to action for the Spurs after missing multiple games. Barry, who missed four games with back spasms, scored six points in 19 minutes. Horry, who missed the last five with an abdominal contusion, had two points in 10 minutes.