Richardson had 20 points and 13 rebounds for the Suns, who have won three in a row. Amare Stoudemire donated 30 points and nine rebounds. Grant Hill tallied 21 points and nine boards for Phoenix, which got 16 points and 10 assists from Goran Dragic.
Kevin Durant poured in 36 points and has now scored at least 25 points in 29 straight games. Durant continues to inch closer to legend Michael Jordan, who scored 25-plus points in 40 straight games during the 1986-87 season.
Down 86-82 less than two minutes into the fourth, Oklahoma City went on a 16-2 run to build a 10-point lead. Durant tallied eight points during the burst, including a jumper to make it 98-88 with five minutes to play.
The Suns responded in a big way, closing the contest out on a 16-4 spurt to claim victory.
A Stoudemire layup and pair of Hill free throws got Phoenix within 100-97 with 1:25 remaining. Green put the Thunder up five with a pair of foul shots at the other end.
Stoudemire's three-point play cut the gap to 102-100 with one minute left on the clock. Following a missed jumper by Durant, Richardson made two free throws to deadlock the tilt with 40.2 seconds remaining.
Oklahoma City's cold streak from the field continued as Westbrook was off the mark on a long jumper. Green pulled down a big offensive rebound but missed a putback attempt. Hill grabbed the rebound and called a timeout with 13.4 ticks to go.
Richardson then drove the lane and put home a floater to give the Suns a 104-102 edge with 0.7 seconds remaining. Green's contested three-pointer at the opposite end hit off the rim as time expired.
The Thunder held a 52-51 lead following a back-and-forth first half.
Ahead 61-58 with less than nine minutes to go in the third, Phoenix ripped off 12 consecutive points to gain some breathing room. Dragic and Hill each made threes during the stretch, which Richardson ended with a layup for a 73-58 advantage with over 6 1/2 minutes remaining.
Oklahoma City fought right back with 11 straight points to get within 73-69 with less than four minutes to go. The Suns held an 82-78 margin heading to the fourth.
Oklahoma City snapped a nine-game skid to the Suns with a 117-113 win in Phoenix on December 23...The Thunder franchise hasn't won 10 in a row since an 11-game run from November 7-24, 1996...Phoenix went 51.3 percent from the field, while the Thunder made 44.2 percent of their shots...The Suns went 17-of-27 from the foul line, while Oklahoma City made 22-of-24 shots from the charity stripe...Suns guard Steve Nash missed the game due to injuries to his back and abdomen.