Rainey, despite being reduced to 14 players for three-quarters of their AIL game with Queen's, fought bravely to win 23-21 at Upper Malone.
The visitors, who had Johnny Lees red carded for an illegal tackle, had the wind in the first half but finished it 14-6 behind after Ritchie McMaster goaled tries from Damon Hall and Stuart Hooks.
After the break, though, Mark O'Connor kicked his third penalty and Nial O'Kane crossed for a try which O'Connor goaled to put them 16-14 in front.
Queen's came back with an excellent converted Stuart McIlwaine try but, with 17 minutes remaining, Michael Shiels crossed for the visitors to level and O'Connor kicked the conversion to bring his tally to 13 points.
Another team to come from behind was City of Derry at Old Wesley. They trailed 16-10 at half-time but tries from Jack Caithness and David Houston, added to Peter McFeeley's early effort, won a thriller 25-24. Mark Robinson kicked two penalties and two conversions.
Ulster results: 2A - Ballymena 8 Bective 3, Highfield 12 Banbridge 19, Old Wesley 24 City of Derry 25, Queen's 21 Rainey 23.
Div 2B - Instonians 8 Tullamore 14, Greystones 27 Ards 3, Armagh 8 Suttonians 5