Afghanistan scored 151 for 3 off their 20 overs, and when Oman slumped to 0 for 2 in the first over, their chances seemed slim. But a hundred stand between Nilesh Parmar (66) and Adnan Ilyas (52) took them to the brink of victory and five were needed at the start of the last over.
In a dramatic finale, two were needed off the last ball. The batsman swung and missed and as Afghanistan celebrated, believing in error that the wicketkeeper had stumped him, the Omani batsmen scrambled a single to tie the game.
The competition rules dictated there should have been a bowl-out but the officials decided that the pitch had been damaged by spectators charging onto it at the conclusion of the match.
"I don't know whether to be happy or sad," Afghanistan's coach Taj Malik said. "We could have won, we could have lost. We should have won."
In the third-place play-off, Kuwait beat UAE by three runs.