The Rajans, who had hitherto been riding high in the Under 17 Div. One tournament, met their waterloo at he Prison Grounds in Pallekele.
Their opponents, the Sebastianites, played positive cricket to beat them by 20 runs on the Parabola method.
Batting first on winning the toss, the visitors were bowled out for only 171 on a smallish ground.
However, their bowlers never let the Rajan batsmen get away and kept picking up wickets.
Janishka Perera made the only half-century of the match, getting an attacking 60 runs which contained six fours and three sixes. Nishita Abilash and Praveen Cooray came up with useful twenties.
Bandara Ekanayake came to the fore again when the home team batted, getting 26. Regular contributors Isuru Dayananda and skipper Sachchintha Senanayake entered the 20s.
Nipun Pieris (2), Sashika Perera (2) and Praveen Cooray (3) helped to derail the Rajan chase.
St. Sebastianís will now meet St. Anthonyís in the quarter-final in a couple of days.
St. Sebastians 171 in 49.2 overs
(Nishitha Abilesh 26, Janishka Perera 50, Praveen Cooray 21, Bandara Ekananayake 4-29).
Dharmaraja 130-9 in 38.3 overs
(Bandara Ekanayake 26, Isuru Dayananda 28, Sachchintha Senanayake25, Nipun Pieris 2-26, Sashika Perera 2-18, Praveen Cooray 3-21).