Riewoldt has kicked 17 goals in his first five games this season and he was brilliant in the Saints' surprise win over Essendon in round four, booting five.
Leppitsch said the inclusion of Daniel Merrett after a two-match suspension would boost the Lions defence on Friday night, but there were other options in the quest to halt the Coleman Medal leader, who is tied with Port Adelaide's Jay Schulz.
"Joel Patfull has played on Nick for a long period of time," Leppitsch said in Wellington.
"I actually played on Nick when he first started but I can't come out though. I'm not too fit at the moment.
"Other than that, we've got young key defenders and Daniel Merrett is coming back into the team as well so there's a couple of contingencies there.
"Nick's form has been unbelievable for an old man. To still be running around and being as athletic as he is at the moment, it's very impressive for a guy of his age."
The Lions' own champion forward, Jonathan Brown, returned to form in his 250th match last Thursday, booting four goals.
Captain Jed Adcock said Brown's contribution was still vital to the Lions.
"He's important for our young forwards and developing those guys," Adcock said.
"Obviously Browny won't be here for much longer, so it's important he contributes where he can.
"He is kicking goals and he's our most potent forward at the moment, so it's important he keeps up and about."
Winless after five games, Adcock said "grinding" out a positive result soon was important to get the young team on track.
"At the start of the year we spoke about we knew we had a hard draw early, but we're actually playing some pretty good footy against some of the teams you would consider top-four teams," he said.
"The last couple of weeks we've played some poor footy in patches and against Port we played pretty much three quarters of poor footy.
"It's important for a young group that you get a win on the board for starters and you never know what's going to happen after that."
