Ballyclare Ladies seemed to be on course to collect full points in Magherafelt, until Rainey weighed in with two late strikes which sealed a 4-2 win.
A Jaquie Hanley goal separated the sides at the interval and after the hosts levelled the scores, Jordan Jones regained the lead, only for the locals to dominate the final quarter and secure the Senior 1 points.
Hanley opened the scoring from a penalty stroke, awarded when the ball struck a defender on the line and later at the opposite end Sara Coulter came to the rescue when she pulled off a stunning save at the base of the post, also from a penalty stroke.
Rebecca Campbell, Suzanne Dickey and Rebekah Beattie all showed up prominently in visiting attacks, but were thwarted by the competent home goalie.
So Caroline Darragh’s girls turned round one up against the pre-match favourites, who, however, equalised early in the second session from a penalty corner.
Undeterred by this reverse the ‘Clare girls regained the lead when Jones applied the finishing touch to a Campbell cross. But that was as good as it got.
Dominating the final 15 minutes, the Rainey girls first of all levelled the scores and then added two more to keep them in the slipstream of leaders, Banbridge.
The defeat dropped Ballyclare to seventh spot, but well clear of Larne and Victorians, who remain several points adrift at the foot of the table.
Ballyclare Ladies’ panel: S Coulter, J Hanley, C McGookin, K McLeod, L Holmes, S Dickey, C Darragh (C), R Beattie, L Ashcroft, R Campbell, J Jones, D McClenaghan, J McGowan.
On Saturday Ballyclare make the long journey across the border to take on Raphoe, who are proving to be the dark horses in Senior 1.
n Elsewhere in Senior 1, Ballymena Ladies got the better of Larne Ladies with a 2-1 win at Larne Grammar School.
Aimee Logan’s opening strike for the Braid girls was cencelled out when Larne’s Beth McVeigh fired home an equaliser. However, the visitors had the final say when Emma Gillespie scored the match-winning goal in the second half.
n In Senior 2, Carrick Ladies had too much for nieghbours Greenisland. Inspired by a Christine Waide hat-trick, Carrick cruised to a 6-0 win. Their other goals came courtesy of Aoife Burgess, Ashley McConnell and Rachel Lynas.