Wednesday have got the better of Brighton 2-0 at home in the first leg of the Championship playoff semi-final tie.
The Owls took the lead at the Hillsborough Stadium through Lee Wallace on the stroke of half time.
Kieran Lee doubled the advantage for the home team in the 73rd minute, as Brighton ended the game with 10 men due to injuries.
Former Wednesday star Waddle was following the match, and he suggested that Carlos Carvalhal’s side should have won it by a bigger margin.
The former Newcastle United and Tottenham Hotspur attacker also warned that the tie is not over yet.
"This game's not finished,” said Waddle on BBC Radio 5 live on Friday evening (21:46). “Sheffield Wednesday could have put it to bed.
"Give Brighton credit, they've had a horrendous night with injuries and everything's been against them.
"I thought Sheffield Wednesday were excellent in spells tonight. I just hope they don't regret killing this game by three or four."
Well done swfc great result should have put it to bed tonight what an atmosphere old days back great support— Chris waddle (@chriswaddle93) May 13, 2016
Over the course of the 90 minutes at the Hillsborough Stadium, hosts Wednesday had 63% of the possession, took 16 shots of which just four were on target, and earned five corners.
Visitors Brighton had 37% of the possession, took seven shots of which only one was on target, and earned four corners.