The Ospreys, with young outside half Matthew Morgan in sparkling form, took the first half honours before the Saints’ scrumagging took its toll after the break with three tries coming from their forwards.
Morgan had a dream night with the boot, kicking five penalties and the conversion of Sonny Parker’s interception try just before the break, but the Saints pack then took charge with hooker Hatley and flanker getting the second half tries after Russian international wing Vasily Artemyev had crossed for the visitors midway through the first half.
The Ospreys did not help themselves in having two players sent to the sin bin in the first half but they still gave the Saints plenty to think about.
Ospreys: Try: S Parker; Con: M Morgan; Pens: M Morgan (5)
Northampton Saints: V Artemyev, D Hartley (2), C Clark; Cons: R Lamb (3); Pens: R Lamb, S Myler
