Ireland stunned two-time world champions West Indies, chasing down a steep 304 in Nelson on Monday.
Opener Stirling scored 92 and shared in a 106-run partnership with Joyce (84) while Niall O’Brien added 79 not out to guide Ireland to 307 for six in 45.5 overs after West Indies had scored 304 for seven.
Lendl Simmons made 102 and Darren Sammy posted his highest ODI score of 89.
For Ireland, George Dockrell took three for 50.
“We know what we are capable of and we believed going out the pitch today, that we could win not only this game but other games in the competition and we want to continue that,”Ireland captain William Porterfield said.