The sun was shining at Energia Park, with a windy breeze flying around that was behind the home side from the opening whistle.
Leinster made a dominant start, crossing for the first score after 1 minute. Captain Conor O’Tighearnaigh going over from close range after a break from flanker Cruise-O'Brien. Casper Gabriel added the conversion.
Leinster would add two more converted tries before the clock hit 15 minutes, with Hugo McLaughlin and Ciarán Mangan finishing clinical attacks, a result of Leinster's backline working the ball with speed and intensity.
Ulster settled after and produced their opening score through Dungannon RFC centre, James Girvan, who made an excellent line break around the halfway line and went all the way to score in the 20th minute. James Humphreys slotted in the conversion to make the scoreline 21-7.
Leinster would add four more tries before half-time, through Hugo McLaughlin, Mahon Ronan and Cruise-O'Brien (2).
At half-time the scoreline was 45-7 to the home side.
HT: Leinster 'A' 45-7 Ulster 'A'
Ulster showed a lot more of their potential in a competitive second half.
Cormac Foley scored the first try of the second period for the hosts in the 47th minute, with Gabriel's conversion taking the scoreline to 52-7.
Ulster's outside centre, James Girvan, was able to score his second try of the contest in the 56th minute, after a break from Bradley McNamara who then fed Bevan Prinsloo. The inside centre and Instonians man galloped into the Leinster 22 and was able to offload to Girvan on his support line. Replacement fly-half, Owen O'Kane, added the conversion.
Leinster scored their ninth try on the hour mark, with hooker, Stephen Smyth, dotting down after a powerful maul. Gabriel's conversion brought the scoreline to 59-14 with twenty minutes left.
Ulster kept trying to play an expansive style of rugby, and it paid dividends in the 66th minute, after quick ruck ball from scrum-half Clark Logan was recycled out wide to replacement wing, Ethan Graham, who produced a fine finish in the left corner for Ulster's third. Owen O'Kane added the extras from the tee.
With the bench emptied, Ulster fought well to keep the home side at bay, with Callum Johns and Tom Brigg making good defensive efforts late on.
However, Leinster would have the final say in the match, with Jack Deegan scoring Leinster's tenth with the clock in the red.
At full-time the scoreline finished 64-21 to the home side, who were in control of the contest. Ulster's young side gained valuable experience for the future.
FT: Leinster 'A' 64-21 Ulster 'A'
Scorers:
Leinster A:
TRY: O’Tighearnaigh, McLaughlin (2), Mangan, Cruise-O'Brien (2), Ronan, Foley, Smyth, Deegan
CON: Gabriel (7)
Ulster A:
TRY: Girvan (2), Graham
CON: Humphreys, O'Kane (2)
Teams
Ulster 'A':
1. Jacob Boyd, 2. Henry Walker, 3. Bryan O’Connor, 4. Paddy Woods, 5. James McKillop (C), 6. Matthew Dalton, 7. Jon Rodgers, 8. Tom Brigg, 9. Clark Logan, 10. James Humphreys, 11. Ben Moxham, 12. Bevan Prinsloo, 13. James Girvan, 14. Aitzol Arenzana-King, 15. Bradley McNamara
Replacements: 16. Charlie Hargy, 17. Niall Carville, 18. Blake McClean, 19. Callum Johns, 20. Adam Milligan, 21. Sam Harper, 22. Owen O’Kane, 23. Rynard Gordon, 24. Ethan Graham, 25. Angus Graham
Leinster 'A':
15. Hugo McLaughlin, 14. Charlie Molony, 13. Jack Deegan, 12. Ciarán Mangan, 11. Jonny O’Sullivan, 10. Caspar Gabriel, 9. Cormac Foley; 1. Alex Mullan, 2. Stephen Smyth, 3. Andrew Sparrow, 4. Conor O’Tighearnaigh (C), 5. Mahon Ronan, 6. Billy Corrigan, 7. Inigo Cruise-O’Brien, 8. Josh Ericson
Replacments: 16. Rian Handley, 17. Max Doyle, 18. Niall Smyth, 19. Artur Symkovskiy, 20. Sean Walsh, 21. Tadhg Brophy,
22. Tom Larke, 23. Johnny O’Sullivan, 24. Paddy Moore