HOUSTON - It's taken all of two games for newly-acquired Houston Rockets forward Josh Smith to make the sort of impact that reinvigorates hopes and reignites expectations for a team straining mightily against them.

Along with guard James Harden, Smith keyed a second-half offensive resurgence and Houston rallied from a third-quarter deficit to race past the Dallas Mavericks 115-104 on Sunday at Toyota Center.

Harden posted his eighth career triple-double and second this season, finishing with 23 points, 15 rebounds and 10 assists. Smith added 16 points off the bench and energized the Rockets (24-22) for a second consecutive game following his acquisition from the Clippers on Friday.

"I feel comfortable," Smith said. "It might have been a little different story if this had been my first time getting to know these guys, but being able to get an opportunity to play with the same team around the same group of guys is awesome."

Forward Trevor Ariza scored a season-high 29 points, 16 in the first quarter, and shot 11 of 15 from the floor, including 6 of 9 from behind the 3-point line as Houston managed a 28-point second-half turnaround.

Dallas entered the fourth period shooting 53.4 percent (31 for 58) but collapsed late. Forward Chandler Parsons poured in a season-high 31 points against his former team, but his teammates could not keep pace.

Forward Dirk Nowitzki added 19 points but was scoreless over four fourth-quarter minutes. Guards Raymond Felton and Wesley Matthews scored 16 and 15 points, respectively, but combined for just six in the final period.

Center Sal Mejri, starting for the injured Zaza Pachulia, had 10 points, 11 boards and three blocks but also had three late turnovers.

The Mavericks (25-21) hit 15 of 30 3-pointers in defeat. They led 70-59 when Nowitzki buried a 3-pointer with 7:36 left in the third quarter but their defense had no answer when Smith and Harden got the Rockets rolling.

"They are tough to defend with the roster they have regardless of who's out there," Mavericks coach Rick Carlisle said of the Rockets. "They are very deep and they didn't even have (center Dwight) Howard playing. It's going to be tough.

"Smith is a guy who played well for them last year and he's playing well for them this year, so he doesn't make it any easier."

Following an offensive showcase where both teams shot above 50 percent in the first quarter, only Dallas kept pace in the second period.

Keyed by Nowitzki, who scored on three consecutive Mavericks possessions, Dallas seized the lead with a 13-0 run that included Houston missing six consecutive field goals while committing two turnovers over a four-plus minute stretch. The Rockets missed 15 of 21 shots in the second, and when Parsons closed the period with a trey and three free throws with 11.9 seconds left, Dallas led 58-50 at the break.

"You can never get comfortable against a team like Houston," Parsons said. "They are very talented in so many different ways. We allowed them to make plays and get easy shots and open 3s."

Following a 3-for-12 first half, Harden found a groove early in the third quarter, scoring 10 quick points to keep the Rockets afloat. The Mavericks held a 73-65 lead when Smith entered at the 5:35 mark of the period, and in a flash he sparked the Rockets' 11-4 run into contention.

Felton nailed a trey to keep the Mavericks ahead 85-84 entering the fourth but by then Houston had wrangled momentum. Ariza, reserve guard Jason Terry and Smith drilled 3s in succession, and after guard Ty Lawson added a three-point play before Terry buried another 3, the Rockets built their lead to 101-91 with 8:30 remaining in the contest.

"Josh brought that extra burst that we needed," Harden said. "It's just perfect timing."

NOTES: The Mavericks were without C Zaza Pachulia (right lower leg) and F Jeremy Evans (right shoulder). Should Pachulia respond well to rest, he could return to the lineup on Tuesday against the Lakers in Los Angeles. ... Rockets PG Patrick Beverley returned to the lineup after missing three of four games with a left ankle sprain while C Dwight Howard remained sidelined with the same ailment. Howard missed his second consecutive game after suffering the injury in the opening minute against the Pistons last Wednesday. ... Rockets interim coach J.B. Bickerstaff stuck with his small-ball lineup, pairing Trevor Ariza and Corey Brewer at forward alongside C Clint Capela. Ariza provides the defensive versatility to validate the change, defending power forwards with an effectiveness that makes Bickerstaff amenable with the switch.