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PHOENIX -- Their best regular-season month in franchise history is over. The Oklahoma City Thunder look for even better things ahead in the playoffs.

Kevin Durant and James Harden scored 22 points and the Oklahoma City Thunder completed the best month in franchise history with a 116-98 victory over the fading Phoenix Suns on Wednesday night.

Michael Westbrook added 16, Serge Ibaka 15 and Kendrick Perkins 13 as the Thunder won their fifth in a row, 11th in their last 12 and 50th of the season.

It's the first consecutive 50-win seasons for the franchise since 1998.

"After my first two seasons, we went from 21 wins to 50 win seasons, that is a big turnaround for us and something that can't be overlooked," Durant said. "I know it is the regular season and it means a lot, but in the postseason it is kind of out the window. It does feel good to get 50 wins as a young group."

Their 14-2 March was the best monthly record in franchise history. As the Seattle SuperSonics, they went 14-3 twice -- in March of 1994 and November of 1996.

"We're just on a roll," Harden said.

Vince Carter, now coming off the bench for Phoenix, scored 28 in the Suns' fourth straight loss. Three of Carter's top four scoring games for the Suns have come against Oklahoma City. Carter was benched three games ago in favor of Jared Dudley.

"I just kept playing through it," Carter said. "I just tried to relieve those guys and play tough for them. They played a rough one last night [a loss at Sacramento] and we pride ourselves on everyone contributing, so I did just that. I was being aggressive and hit a few shots in the post and just got going and stuck with it."

Referee Kenny Mauer threw out Suns reserves Aaron Brooks and Zabian Dowdell with 1:05 to play.

Oklahoma City outscored Phoenix 37-25 in the fourth quarter.

"It was a bad night for us," Suns center Marcin Gortat said. "We played terrible defense. We played with no toughness or physicality."

Phoenix trailed 55-51 at the half and never caught the Thunder after that.

The Suns cut it to one twice, the last time at 60-59 on Gortat's dunk. But Westbrook made a driving layup, Dudley was called for an offensive foul, then Westbrook made a 7-foot runner and Oklahoma City led 64-59.

Collison's 20-footer with 6 seconds left put the Thunder up 79-73 after three quarters.

Harden sank a 3-pointer and had a three-point play sandwiched around Eric Manor's 3-pointer in a 8-2 spurt that put Oklahoma City up 87-77. Durant's 3-pointer with 5:18 remaining put the Thunder ahead 92-80 5:18 from the finish.

Oklahoma City outscored Phoenix 23-9 to start the final quarter to go up 102-82 after Perkins made four free throws in a row.

"We just can't seem to put any offense together to start the fourth quarter," Suns coach Alvin Gentry said. "That's where most of the teams seem to be getting separation between us."

Thunder coach Scott Brooks called Westbrook the unsung hero of the night.

"He's had better stats in the past, but he really controlled the game," Brooks said. "He was active on the ball and I thought his command of the game put us in a position to win tonight."

Game notes

With their 115-114 victory over Golden State on Tuesday night, the Thunder became the fifth team in NBA history to win eight overtime games in a season. ... Phoenix fell two games under .500 for the first time since a Feb. 4 home loss to Oklahoma City. ... The Thunder completed their fifth sweep of back-to-back games this year.