Ireland 141 for 4 (Tector 54*, Dockrell 49*) won Zimbabwe 140 for 6 (Bearle 36, Bennett 27, Delaney 2-8, Little 2-21, Young 2-27) with six wickets.
With 141 runs to chase, it looked as if even this match could go to the end like the last two matches when Ireland stumbled to 37 for 4 in seven overs.
But Dockrell and Tector met the Zimbabwe threat and quickly put Ireland in the driving seat. They eventually cruised to victory by eight balls.
The momentum shifted after the 12th ended. Ireland was on a roll even then, and demand was rising. Tector, who played a key role in Ireland’s chase in the second T20I, was batting on 13 off 21 balls. Zimbabwe needed 69 off 48 balls.
Dockrell then hit Zimbabwe stand-in skipper Ryan Burle for two sixes in the 13th over of 16 overs, and Ireland had another 12 in the next over, bowled by Wellington Masakadza, to bring the equation down to 41 off the last six.
Tector then changed gears himself and ended up racing to a half-century off 41 balls as he finished the series as its top run-scorer. However, he was the first to admit in his post-match chat that it was Dockrell who engineered the win by taking the pressure off him when he struggled early, on a pitch where the ball often remained low.
Zimbabwe, who were already without the suspended Sikander Raza, had to appoint a third captain for several matches in this series with Sean Williams out due to a side injury he sustained during the second T20I.
This led to a major reshuffle, with opener Tadiwanashe Marumane and fast bowler Trevor Gwandu also making way with leg-spinner Brandon Mafuta, left-arm spinner Masakadza and batsman Tony Munyonga coming into the side.
After its accession, Zimbabwe continued to endure conflicts at the highest levels. Tinashe Kamunhukamwe, who was sent to the opener after a brilliant strikeout at third on Saturday, was trapped at pound-for-pound off Josh Little’s first ball.
But Brian Bennett, who made 1 and 0 in his first two caps, made the most of his promotion to third. Irish bowlers targeted him with short balls, but he was not shy about pulling and pinning his way out. From the bombing. Zimbabwe scored just 26 in their first five overs, but ended the power play on a high when Bennett pulled Barry McCarthy for six in a row.
But Gareth Delaney turned the game around in the next over, first trapping Wessly Madhevere lbw after mistaking the pull to one that stayed low and then getting Bennett to a 19-ball 27.
Pearl was about to get off the first ball, but Tucker couldn’t catch the inside edge. Pearl then toured with Munyonga before Craig Young fortified the latter.
As in the second T20I, Burl and Madande put on a defiant stand, adding 55 off 47. But Young gave Ireland a crucial breakthrough by bouncing Madande before Burl drove Little straight to Delany at cover.
Mafuta and Luke Jongui added 24 runs for the seventh wicket, taking Zimbabwe’s total to 140.
Zimbabwe again started well with the ball, with Richard Ngarava trapping Paul Sterling in front in the first half. Blessing Muzarabani, who came into the attack in the fourth over after Masakadza opened the bowling with Ngarava, also batted on his first over when Andy Balbirnie miscued a pull to Burl, who got a good catch going back from midwicket.
Lorcan Tucker swept Masakadza for a boundary but lost his stumps while trying to bowl the next ball.
Curtis Campher joined Tector at the crease but was struggling to keep the spinners away, especially Mafuta, and the leg-spinner eventually got a leading edge off him that was eaten up at cover.
This brought Tector and Dockrell together, and the two proceeded to complete the chase almost faultlessly, with Dockrell hitting the winning runs for the second successive match.
Abhimanyu Bose is a sub-editor at ESPNcricinfo