Scotland were struggling on 71 for five in the 23rd over when incessant rain set in at Stormont. Having seen the weather forecast, Watson chose to bat first to give his batsmen as much time at the crease as possible.
Fending off the back foot, Majid Haq, the proud owner of Scotland's best ODI bowling figures after Thursday's heroics, became the first of three victims for Ryan ten Doeschate, the Essex all-rounder. Fraser Watts struck the ball cleanly to reach 19 before timing a flat pull so sweetly that the fielder at fine leg didn't have time to think before the catch flew into his hands.
Navdeep Poonia, who made 40 against West Indies, looked comfortable until he hit a checked drive straight to mid-off. Watson was cleaned up by a Ten Doeschate cutter to make it 51-4.
Neil McCallum's resistance ended with a thin edge behind, but that was the last action of the day. Scotland play Ireland at Stormont in tomorrow's series finale, which will start at 10.15am.