Crocked Purse missed out on Tuesday night's Carling Cup defeat to Scunthorpe United as the Owls – who had only conceded once in four games prior to Glanford Park – conceded four goals.
One of those came from the penalty spot after Richard Hinds was red-carded for chopping down Jonathan Forte.
Former Iron centre-half Hinds, who was standing in for Purse, is now suspended for three matches, meaning Irvine's options in the heart of his defence are severely stretched.
Only Mark Beevers remains as a specialist centre-half, although right-back Lewis Buxton could be switched to the middle in an emergency.
Full-backs Daniel Jones and John Otsemobor were handed rare starts on Tuesday as Irvine made six changes from the side which beat Brighton in League One last weekend.
And despite refusing to throw in the towel at 3-0 down, the 10 men finished at a respectable 4-2, leaving Irvine with mixed emotions.
"We have a good squad here and I sent out a team that I thought was very capable of getting a result," said the Wednesday manager.
"It's not like they were a team of kids, they are good players and if you are asking me did they stake a claim for Saturday, I would say that one or two did and one or two didn't.
"We gave it a go, but the red card obviously doesn't help," he said. "We kept going and that would be something I would be very disappointed if we hadn't done. But goals change games and to have lost the one in injury time, especially when we had comfortable possession of the ball, was very poor.
"It was poor that we lost possession where we did and it was poor how we defended when we lost possession.
"And to concede within three minutes (of the half restarting), again with poor defending, was bitterly disappointing," added Irvine.
Iron's win continued Wednesday's winless run in Scunthorpe that stretches back to 1958.
"It was a fantastic game of football," said Scunthorpe manager Nigel Adkins. "I thought we played some really good football, passed the ball about and created good opportunities.
"We've scored four and could have scored more."
Wednesday have sold out their 1,000 ticket allocation for Saturday's game at Victoria Park, but an extra batch of seats have been released for Owls fans which are available from the club's online shop only.
The club have reduced tickets for next Wednesday's Johnstone's Paints Trophy tie against Notts County.
Tickets are priced 5, 2.50 concessions.