Dehradun: Ireland were skittled out for 114 in a 109-run defeat which leaves them 2-1 down in the ODI series against Afghanistan in India.
The Irish were in a good position after dismissing the Afghans for 223 with James Cameron-Dow taking 3-32.
Ireland were making decent progress on 82-4 before a collapse which saw six wickets fall for just 32 runs with Aftab Alam posting 4-25.
The sides meet in the final ODI in Dehradun on Sunday.
Afghanistan won the T20 series 3-0 and their only defeat to the Irish came in the third one-day encounter on Tuesday.
They were struggling on 81-6 before a 50-run partnership between Asghar Afghan (54) and Mohammed Nabi (64).
Nabi then combined with Rashid Khan (52) for an invaluable eighth-wicket stand of 86 before the innings came to an end with five balls to spare.
Andy McBrine (2-37) Boyd Rankin (2-50) both picked up two wickets as the Irish were set a modest target.
However, it proved well beyond them despite an opening stand of 31 between captain William Porterfield (21) and Paul Stirling (11).
Simi Singh hit 20 and Kevin O'Brien top-scored for the Irish with 26 before the wickets tumbled and the Irish were all out in 35.3 overs.
Alam was ably assisted by Rashid Khan (2-22) and Mujeeb Ur Rahman (2-25) in an impressive display from the Afghan bowlers.