Mayo scored 18 of his 21 points in the second half, and Memphis snapped a 13-game losing streak to Dallas with a 102-82 victory Sunday.
"It's like that bully in school that's always coming and beating you up, and standing up to him," Memphis forward Hakim Warrick said of beating the Mavericks. "We were finally able to go out and get that win against them."
Mayo connected on 5 of 8 shots outside the arc as Memphis shot 47 percent from 3-point range for the game.
Memphis jumped ahead early on 67 percent shooting in the first half but went into the break with just a 50-45 lead.
Dallas had outscored opponents 59-41 after intermission in the last three games, including erasing a 29-point deficit to defeat the Minnesota Timberwolves 107-100 last Tuesday, but couldn't mount a comeback against Memphis.
"We've been down 10, 12, 16. We were even down (29) against Minnesota," Nowitzki said. "We're just not playing well early now. We've always got to fight back, and we did that over the last couple of weeks.
"At some point, all the fighting back is going to haunt you. You waste a lot of energy trying to fight back," he said.
Prone to struggling at the start of the third period, the Grizzlies traded leads throughout the quarter before taking control with a 9-3 run, helped by five Dallas turnovers.
Mayo scored 10 in the period, while Gay had eight and Memphis led 76-68.
"Down the stretch, we really buckled down, especially defensively," Warrick said. "The open shots they got, we just ran them off, and made them work a little bit harder."
Mayo's scramble for the ball and flip to Warrick for a dunk gave the Grizzlies 95-80 lead with 3:39 to play. Memphis' lead would grow to 22 on a 3-pointer by Mayo.
"There's not one play that stands out," Dallas point guard Jason Kidd said, "but all of a sudden, we were down nine, and it just kept growing. The first group, we just couldn't get it back."
The Grizzlies outscored the Mavericks 26-14 in the final period. Even Nowitzki couldn't help at that point, missing all three of his shots in the quarter as the Mavericks shot 23 percent for the period.
Memphis built a 12-point lead early. Nowitzki was the offensive force for the Mavericks, scoring 16 of Dallas' 25 points in the first period.
The Grizzlies, however, could not maintain the shooting pace, missing 10 of 11 shots to open the second quarter. That allowed Dallas to cut into the lead with Nowitzki taking a break.
When he did return, the 7-foot Nowitzki immediately went to the basket with the shorter Memphis forwards on him. Nowitzki ended up with 22 in the half to lead the Mavericks.
"Clearly, the energy level for us went up in the second half," Memphis coach Marc Iavaroni said. "It was a good response to Dirk going crazy in the first half."
Gasol matched Nowitzki offensively, hitting eight of 10 shots en route to 19 first-half points. That helped Memphis carry a 50-45 lead into the break.
"I just felt like I was in a good position to score," Gasol said of his early offensive production.
The Grizzlies outscored the Mavericks 48-32 in the paint, and 26-12 in second-chance points, fueled by a dozen offensive rebounds. Dallas entered the game as the league's best rebounding team at 45.3 a game. Memphis was last with an average of 38.5 boards. Despite that, the Grizzlies outrebounded the Mavericks 43-34.
"They dominated in every statistical category," Mavericks coach Rick Carlisle said. "You have to give them credit. We made some runs, but we could never sustain it. They battled hard and came out like a team that was tired of losing games."
- Memphis G Steve Francis and F Darius Miles, obtained last month, were available for the first time. Francis was on the inactive list, while Miles dressed and played the final 1:46.
- Dallas G Jason Terry hit a 3-pointer late in the third period, giving him his 22nd straight game with a 3.
- Memphis F Quinton Ross missed Sunday's game with back soreness. Memphis' last win over the Mavericks was Nov. 26, 2005, at Dallas.
- The Grizzlies last home win over Dallas was Feb. 17, 2004, at their former home The Pyramid. It was the first time Memphis has defeated the Mavericks in the FedExForum after 10 straight losses, including the postseason.