Lawes was at his destructive best for the Saints, putting in numerous bone-crunching tackles and dominating restarts during an eye-catching performance just two weeks before England launch their autumn international campaign.
“Courtney was sensational, not just in his restarts, but his defence as well,” Northampton rugby director Mallinder said.
“He is consistently making big tackles, he consistently makes big carries and he is doing that for 80 minutes now, which is where I think he has moved on in the past few months.
“He was in and out of games a little bit in the past. Now he is the sort of complete player for the full game.”
Lawes, 24, has had his share of injuries during recent seasons, but he is now unquestionably operating at maximum efficiency.
The only injury scare for Saints — and England boss Stuart Lancaster — was an ankle problem suffered by hooker Dylan Hartley just before half-time, although he managed to play on afterwards.
Number eight Samu Manoa, lock Christian Day and full-back Ben Foden scored tries for the Saints, with fly-half Stephen Myler converting all three touchdowns and booting two penalties as Northampton triumphed.
Wales fly-half Dan Biggar posted all the Ospreys’ points from a try, conversion and three penalties, yet they now have a mountain to climb in Pool 1, a group that also includes reigning French champions Castres, conquerors of Northampton eight days ago.
Scorers for Northampton: Tries: Manoa, Day, Foden. Cons: Myler 3. Pens: Myler 2.
Scorers for Ospreys: Tries: Biggar. Cons: Biggar. Pens: Biggar 3.
NORTHAMPTON: Foden, Elliott, G Pisi, Burrell, North, Myler, L. Dickson, A Waller, Hartley, Ma’afu, Lawes, Day, Dowson, Wood, Manoa.
Replacements: K Pisi for Elliott (75), Fotuali’i for L Dickson (62), E Waller for A Waller (69), Haywood for Hartley (75), Denman for Ma’afu (61), Clark for Dowson (55), van Velze for Manoa (55).
OSPREYS: Fussell, Hassler, Bishop, Beck, Walker, Biggar, Haberfield, Bevington, Hibbard, A Jones, A Jones, King, R Jones, Tipuric, Bearman.
Replacements: Morgan for Beck (72), D Jones for Bevington (62), Baldwin for Hibbard (69), Ardron for A Jones (54), Lewis for King (69), Jarvis for R Jones (54), Allen for Bearman (47).
Referee: Alain Rolland (Ireland).