In a rearranged fixture, the Royals never got going against Martin O'Neill's men and a resounding beating left them prime candidates for relegation as they struggled to adapt to life in the top flight.
A major upturn in form has occurred since, however - they are unbeaten in five games - and they find themselves out of the bottom three as a result.
A penchant for comebacks has helped their cause, with come-from-behind wins against West Brom and Newcastle followed by Wednesday's rescue of a 2-2 draw against Chelsea, and McDermott believes that they will present Sunderland with a tougher test this time around.
"The lads are fired up for every game and this one is no different," he told a press conference. Sunderland played well against us at the Stadium of Light, got an early goal and went from there.
"But we know it won't be easy for them to come here now with how we are playing and long may that continue."
The Black Cats are currently sitting in mid-table after some struggles of their own, but primed themselves for a surge in the second half of the season with the £5million acquisition of Swansea striker Danny Graham.
"When they and Martin started the season it was difficult, but look at them now," McDermott said.
"They're comfortable in the league and once again Martin is doing a great job, which he always does. He's got good players in and signed Danny Graham and I'm sure he'll be involved."
McDermott signed four players himself during the window, but revealed today how close he had come to pulling off what would have been a surprise capture.
While most thought he was working on a deal for Blackpool's in-demand Thomas Ince, McDermott was actually plotting to sign Tottenham midfielder Gylfi Sigurdsson.
The Iceland international started his professional career with the Royals before moving to Hoffenheim in 2010 after impressing with the Berkshire club.
His stock continued to rise and after an impressive loan spell with Swansea last season, Tottenham signed him on a permanent deal in the summer, but McDermott did his best to get him back in a blue and white shirt before the transfer deadline passed last night.
"We tried to bring him back. We had spoken to Spurs and we made three offers," McDermott added. "I thought at one stage we had a real chance of doing a deal, but unfortunately we couldn't manage to do it.
"Gylfi is a Tottenham player, but we've known him since he was 12 or 13 years old and it would have been great to bring him back."
As a result, McDermott's January business involved Sheffield United striker Nick Blackman, Fulham's Stephen Kelly, Hope Akpan from Crawley and Daniel Caricco from Sporting Lisbon.
It is a player already on his books who has been attracting headlines, though, with the goals of Adam Le Fondre the key to Reading's recent revival.
The 26-year-old has quickly installed himself as something of a super-sub, coming off the bench to score twice at Newcastle and also twice against Chelsea.
McDermott said after the latter game that the former Rotherham man could play for England, while the player himself is just happy to be making an impact.
"You never say never and you strive to play for your country, but I'm a long way from that. It's not for me to say," he told his club's website.
On Saturday's clash and a chance to build on getting out of the bottom three, he added: "As we always do we take it a game at a time and that makes this a big game.
"Since I've been here we've shown the right spirit and character and we have shown that we are never finished. This is a massive game and we need to make sure we start like we finished at Chelsea."
Blackman is in the squad for the first time on Saturday, while Jason Roberts (hip) is ruled out. Noel Hunt faces a late test on an unspecified knock.