After posting 145/6, India spinners spun a web around Ireland batting line-up to restrict them to 93 for eight in their 20 overs and guide India to a comprehensive 52-run win at the Providence Stadium.
Though Mithali (51, 56b, 4x4, 1x6) and fellow-opener Smriti Mandhana (33, 29b, 4x4, 1x6) added 67 runs in 10 overs, the innings never got the required momentum on a track that remained a bit damp due to overnight showers.
Ireland started with some fluency from Shillington (23, 23b, 3x4), who became the first Ireland batter to go past 1000 T20I runs. In reply, Ireland could manage only 93/8 in 20 overs as Deepti Sharma got 2 fo 15 in 3 overs.
If Kaur was the star of the opening win, the team's most experienced campaigner, Mithali Raj, showed the way in the seven-wicket win over Pakistan.
Medium pacers Lucy O'Reilly and Kim Garth impressed for Ireland, the latter especially using her cutters well while the pitch afforded her some moisture to finish win two for 22. The spin duo of Hemalatha and Poonam shared six and four wickets between them in the two matches.
Young Rodrigues hit three fours in his 11-ball-18 but was stumped off Laura Delany's wide delivery when she tried to give charge.
Thereafter, the in-form India skipper Harmanpreet Kaur (7) and No.5 Veda Krishnamurthy (9) departed in quick succession, leaving India reeling at 127/4. As wickets fell at one end, Mithali couldn't shift gears at the other end. She was dismissed in the 19th over, deceived by a slower delivery from Garth, and India's hopes of putting up a substantial total did not quite materialise.