Sam Billings top scored with 89 as England Lions set Pakistan A 216 to win the fifth one-dayer and the series in Dubai.
The Lions, victorious in the first two matches after taking the T20 series before Christmas, got off to a bad start on a difficult pitch.
Captain James Vince was trapped lbw by Mohammad Abbas for three in the second over, and in-form opening partner Dawid Malan was caught behind off former Middlesex team-mate Junaid Khan in the next set of six.
Ben Foakes and Daniel Bell-Drummond both fell to Zohaib Khan, for 13 and 25 respectively, to leave the Lions on 52 for four a ball before the end of the 20th over.
— England Cricket (@englandcricket) January 30, 2016
That brought Billings and Liam Dawson to the crease, and the pair shared a crucial stand of 106 for the fifth wicket.
Hampshire all-rounder Dawson only hit his first boundary shortly before departing for a 64-ball 48 to Fakhar Zaman.
Zaman finished with figures of 5-27, including Billings, with the Kent wicketkeeper hitting eight boundaries in his 101-ball 89.
Tom Curran hit 16 from 17 balls and Toby Roland-Jones added 12, but the rest of the lower order folded as England were dismissed for 215 with five balls unused.