A brilliant century from Andrew Vincent has put Southern Schools in charge against Ulster Schools in their two-day game at Osborne Park.
The Clontarf batsman showed his quality in making 134 as the Southern Schools racked up 310 for 7.
Fellow Ireland U19 international Harry Tector made 63 and Patrick Lynch 38 in an impressive batting display in glorious conditions.
Michael Foster (3-35) was the pick of the Ulster attack.
Tector then took 4 for 38, and Sean Stanton 2 for 29 as Ulster struggled against the quality spin.
James Hunter hit 46 as Ulster closed on 177 for 8, and they face an uphill struggle to save the game when play resumes on Wednesday.
Southern Schools 310/7 (55 overs; Andrew Vincent 134, Harry Tector 63 Patrick Lynch 38, Michael Foster 3-35)
Ulster Schools 177/8 (41 overs; James Hunter 46, Harry Tector 4-38, Sean Stanton 2-29)
Play resumes Wednesday at 11am