Brandan Wright and Darren Collison scored 16 apiece for Dallas. Wright's total was a season high. Chris Kaman added 15 points.
Markieff Morris had 15 points and a career-best 17 rebounds for the Suns, who rallied from 15 down in the third quarter to tie it in the final minute.
Kaman (sprained ankle) and Shawn Marion (strained right groin) left the game with injuries for Dallas, as did P.J. Tucker (sprained knee) and Jermaine O'Neal (eye) for Phoenix.
The game was played on "money-back guarantee night," when those who
Morris' 3-pointer cut Dallas' lead to 87-85 with a minute to go, then Shannon Brown stole Collison's pass and was fouled. Brown made two free throws with 48.5 seconds left to tie it at 87.
But with Sebastian Telfair guarding him closely, Mayo knocked down a 21-footer to put the Mavericks back ahead for good.
Goran Dragic, who scored 15 points but shot only 5 of 14, missed an open driving layup, then Dallas sealed it with eight free throws in the final 19.3 seconds—four by Collison and four by Vince Carter.
Trailing 44-40 at halftime, the Mavericks ran past Phoenix 23-4 to start the third quarter, opening a 63-48 lead with 3:50 to go in the period. Mayo sank his third 3-pointer of the night—in four tries—and Wright, who had not played in three of the previous four games, made consecutive baskets, on a dunk and a layup, to cap the outburst.
Phoenix missed 13 of its first 14 shots in the quarter.
Dragic and Tucker hit 3s to bring the Suns out of their funk enough to cut the lead to 69-62 after three.
Jared Dudley opened the fourth
The Suns jumped out to an 11-1 lead but the Mavericks came back for a 23-all tie after one quarter.
A 7-0 spurt put Phoenix ahead 34-28 on O'Neal's tip-in with 6:41 left in the half, but Mayo's 3-pointer tied it at 36 with 3:52 to go.
Michael Beasley missed his sixth shot in a row, on a 3-pointer, but Morris grabbed his 10th rebound and found Dragic for a 3-pointer to put Phoenix ahead 43-40 with 44.2 seconds remaining in the half. The Suns led 44-40 at the break.
Dallas had lost four of five and was playing its second game in two nights after losing to the Clippers in Los Angeles 112-90 on Wednesday.
NOTES: Fans with single-game tickets who decide they didn't have a good time can fill out a form to get a rebate. ... Telfair was back after missing one game following the death of his father. ... Morris had nine rebounds in 9 minutes during the first quarter. ... Phoenix is 5-4 at home, Dallas 3-7 on the road. ... The last road win for both teams had been at Cleveland. ... Morris' previous career best was 11 rebounds against Dallas in his rookie season a year ago.