The all-rounder smashed 77 runs off 50 balls, including seven boundaries and six maximums as the UAE scored a challenging total of 176 in their allotted 20 overs.
If Mustafa was buoyed by his performance with the bat after being dropped thrice – 18, 51 and 75, then his confidence certainly notched a level higher by taking three wickets in the final over as Afghanistan were all out for 160 in the penultimate over.
It was the second consecutive triumph for the UAE, who arrived in Bangladesh in confident mood after registering their first win in 15 years over Ireland in their Twenty20 international in Abu Dhabi on Tuesday.
With only one qualification berth for the main event where hosts Bangladesh, India, Pakistan and Sri Lanka await, the UAE will be aiming to keep that momentum.
Their next task is to overcome Hong Kong on Saturday before facing Oman on Monday.
Head coach Aaqib Javed insists the players are now “pumped up” and it’s no surprise after this result.
Skipper Amjad Javed’s decision to bat having won the toss paid dividends with Mustafa and Muhammad Kaleem putting on 83 for the opening stand before Rashid Khan removed the latter.
The 17-year-old leg-spinner then gave Afghanistan the upper hand by removing veteran Shaiman Anwar (11) and skipper Amjad Javed (4) as the UAE were 122-3.
Dangerman Mustafa was then sent back to the pavillion through Amir Hamza as Afghanistan, who sealed the Twenty20 series against Bangladesh in October, frustrated their opponents.
But Usman Mushtaq (23) and Mohammad Shahzad (25) upped the ante, adding 48 from the last five overs.
In reply, Afghanistan lost two quick wickets and were 9-2. But they had no answer to UAE’s bowling unit with Karim Saqid (72), one of three bowlers to reach double figures.
Sensing victory, Mustafa took the final three wickets to seal a memorable triumph.