Chelsea had looked set to be knocked out of the competition by npower League One side Brentford, only for Fernando Torres to spare their blushes with an equaliser.
Elimination would have been unthinkable for the west London club, who were Capital One Cup semi-final losers last week and have already surrendered their Champions League title.
As a result, it is already being reported that interim manager Rafael Benitez could be on borrowed time but, according to McDermott, Chelsea remain a team to be feared.
Since the Spaniard took over his players have excelled on the road - they have scored 23 times in two months - and McDermott knows the threat they will pose at the Madejski Stadium on Wednesday night.
"If you look at Chelsea's away record under Rafa it is phenomenal," said McDermott, whose side are unbeaten in 2013.
"They have got a top manager who did fantastically well at Liverpool and also in Spain, and is now trying to work with that group of players at Chelsea. They are a fantastic team but they are not my business.
"You can look at their draw with Brentford but that's just what the cup is all about. Look what else happened at the weekend. Oldham beat Liverpool, (Aston) Villa went out and QPR were beaten at home.
"Chelsea are still in the cup and that's what matters."
A trip to Stamford Bridge was one of Reading's early initiations upon their return to the Premier League and they actually led 2-1 before succumbing to a 4-2 defeat, with an offside Torres goal giving McDermott a bitter-tasting welcome to the top flight.
He says he is over that disappointment now, though, and is heartened by the way his side have performed since the turn of the year.
They are a point and a place shy of safety as things stand, with their case for survival strengthened by come-from-behind wins against West Brom and Newcastle, and McDermott added: "We're getting there, we're working hard and trying to get better as a group. We're all enjoying the challenge.
"We have got some momentum but all we're trying to do is get the results and add the points up in May. I can't dwell on the loss to Chelsea, it's done and dusted.
"We should have got something from the game and the linesman made a mistake, but there's no point me harping on about it."
McDermott has said that he expects the Royals to be doing transfer business right up until the last second on Thursday night, with Blackpool's Tom Ince one of the players he is chasing.
The England Under-21 international is one of the hottest properties outside of the top flight and has been linked with Liverpool, Newcastle and Tottenham, and McDermott has confirmed his club had made an offer.
"We've made a bid and are waiting for Blackpool to come back to us," he said.
"He's a Blackpool player so it's difficult for me to talk about it but he's a good player with potential."
Reading insist the bid remains alive despite reports to the contrary, while McDermott had also acknowledged his interest in Sheffield United's Nick Blackman.
"We've got a couple of targets we've had for a while. Whether that happens time will tell. We had three, one has gone, now we've got two. That's how it works," he said.
McDermott will be without striker Jason Roberts against Chelsea owing to a hip problem, while Noel Hunt has an unspecified knock. Daniel Carrico, a recent signing from Sporting, is unlikely to be involved as he adjusts too life in England.