Afghanistan 189 for 5 (Gurbaz 53, Najibullah 42, Little 2-29) beat Ireland 167 for 9 (Dockrell 58*, Hand 36, Naveen 3-38) by 22 runs
Belfast: Afghanistan beat Ireland by 22 runs, leaving the Irish leading their Twenty20 series 2-1 with two more matches to play at Stormont next week.
A half-century by Rahmanullah Gurbaz helped the tourists to 189-5.
Ireland struggled from the off in their reply as they lost openers Paul Stirling for a duck and Andrew Balbirnie for one to lie 19-2.
Wickets continued to fall steadily and despite a late unbeaten 58 from George Dockrell, they fell short with 167-9.
Ireland had won the first two matches at the Belfast venue and retain a slender lead going into the final two encounters on Monday and Wednesday.
Ireland won the toss and opted to field but they may have regretted that decision when Gurbaz (53 from 35 balls) and Hazratullah Zazai (39 off 40) put together an opening partnership of 90 in 11.2 overs.
Ibrahim Zadran (36) and Najibullah Zadran (42) built on the foundations laid by the openers as the Afghans ended with five wickets remaining.
Najibullan struck five sixes in his 18-ball 42.
Josh Little was the pick of the Ireland bowlers with 2-29.
Lorcan Tucker was the only one of the top five Ireland batters to reach double figures as he slammed 31 off 21 balls, including a six and four fours.
The Irish were struggling badly at 85-7 in the 13th over when Dockrell and debutant Fionn Hand (36) teamed up to put on 74in six overs for the eighth wicket, the former hitting two sixes and six fours.
Ultimately, the home side never looked likely to reach their target and their opponents ran out deserved victors.
Naveen-ul-Haq shone with figures of 3-38 with the ball.