St Kilda had to overcome a 16-point deficit at half time but put the clamps on after the break, kicking eight goals to four in the second half to run out 11.13 (79) to 10.5 (65) winners.
Playing his first game since tearing his hamstring against Collingwood in round three, Riewoldt was rusty early but got more involved as the match wore on.
He started on the bench but eventually played 77 minutes and finished with 1.4.
Lions vice-captain Daniel Merrett probably had the better of their duel, but Riewoldt showed promise with some strong final quarter grabs and a nice goal.
But it was the Saints midfield that eventually wore down a committed Lions outfit.
Leigh Montagna (33 disposals), Lenny Hayes (28) and Nick Dal Santo (26) all covered for the late withdrawal of Brendon Goddard as the Saints kept second spot on the ladder.
James Gwilt and Sam Fisher also worked hard for the winners.
While Riewoldt took all the attention at one end of the ground, embattled Lions spearhead Brendan Fevola had his best game for some time, kicking four goals, including two freak efforts from the boundary line.
For the Saints Stephen Milne had a difficult night against Ash McGrath but finished with two goals, as did fellow small forward Adam Schneider.
Fevola kicked two goals within a minute during the second quarter, and when Black added another, the home fans thought they were in for an upset.
But the constant Saints pressure after half time proved too much, as wave after wave came forward and Gwilt, Brett Peake, Schneider and Dal Santo all banged through goals to steal the momentum.
The quarter was finished with an all-in melee after Lions little man Amon Buchanan shoved Riewoldt in the back following an after-the-siren miss on goal.
Brisbane Lions: 3.1 6.1 7.3 10.5 (65)
St Kilda: 3.1 3.3 7.7 11.13 (79)
GOALS
Brisbane Lions: Fevola 4, Black, Brennan, Buchanan, Cornelius, Polkinghorne, Power
St Kilda: Milne 2, Schneider 2, Dal Santo, Gwilt, McEvoy, McQualter, Montagna, Peake, Riewoldt
BEST
Brisbane Lions: Rich, Redden, Rocklif, Black, Merrett, Fevola
St Kilda: Montagna, Hayes, Ray, Gwilt, Dal Santo, Gardiner
INJURIES
Brisbane Lions: TBC
St Kilda: TBC
Reports: Nil
Umpires: Sully, Wenn, Findlay
Official crowd: 29,329 at the Gabba
The views in this article are those of the author and not necessarily those of the AFL or its clubs
