Ireland lost a last ball thriller in Harare, despite dominating the contest for long periods of the game.
Skipper Andrew Balbirnie, playing in his 200th game, top scored with 121 before having to retire hurt.
He and Harry Tector had added 212 for the third wicket after they had been in early trouble at 25 for 2.
They looked on course to break the Irish ODI partnership record of 227 before Balbirnie edged a high full toss onto his helmet which felled him.
Tector scored his third ODI hundred in his last four innings in the final over and a total of 288 for 4 looked a winning one.
The Zimbabwe reply always seemed to be playing catch-up and at 99 for 4 in the 23rd over with both Ervine and Ballance in the hutch, the home crowd were very quiet.
Ryan Burl though had other ideas and he and Sikander Raza powered their way back into the contest - energised by an assault on George Dockrell, whose solitary over cost 17.
Rain arrived in the 34th over with Ireland two runs ahead on DLS.
An 80 minute delay saw a revised target of 214 in 37 - 39 runs off 22 balls. That looked even more challenging when Raza holed out off Adair.
Still Burl kept finding boundaries and with 13 needed off the last over, it was game on. The run out of Burl looked to have won it, but Brad Evans went six and out to leave the equation at five off two balls.
A single left Clive Madande on strike and he was the home town saviour as he thumped a full toss to long on.
A real thriller, with more to come on Saturday.