The Royals moved to within a point of second-placed West Ham in the Championship table despite falling behind at The Den against opponents fighting for their lives at the other end of the table.
Andy Keogh fired the Lions into a shock lead but Hal Robson-Kanu volleyed Reading level before Adam Le Fondre climbed off the bench to notch the winner.
McDermott was delighted with the way his players made light of a bobbly pitch and hostile atmosphere to record their sixth successive win.
"It was difficult, and different to the last two games against Middlesbrough and Burnley," he said.
"They were more tactical but this was about guts more than anything. The pitch was difficult and to go one down here is not easy.
"The players have fantastic guts, they know how to win games, they know what's required and there's a really good camaraderie between everyone."
Middlesbrough manager Tony Mowbray admitted his players had survived an emotional occasion as they won 3-1 at cash-strapped Portsmouth.
Over 16,000 fans packed into Fratton Park as Pompey, who have been deducted 10 points after going into administration, try to avoid relegation to League One.
It made for a daunting trip for Mowbray's promotion chasers but they ignored the passionate atmosphere to move into fifth place.
"The intensity of the day was always going to make it difficult for us, they have an amazing set of supporters and the atmosphere they generate is first class," Mowbray said.
"On the pitch you look at the quality they possess also, a lot of Premier League experience, and I'm delighted with taking three points."
Ipswich duo Jimmy Bullard and Michael Chopra have been disciplined by the club after a night out in Newcastle.
The pair went out on Wednesday evening and then turned up 20 minutes late for training on Thursday morning.
Blues boss Paul Jewell was left infuriated by their antics but opted for different punishments for the players.
Bullard has been suspended for a fortnight while Chopra -- who scored Ipswich's first goal in Saturday's 3-0 victory against Bristol City -- has been fined two weeks' wages.
"They were in places they shouldn't have been at times they shouldn't have been," Jewell said. "What I've got to try and do is the best thing for the team and the club.
"They're both guilty of the same crime and people may question why they've been treated differently but, in my view, that's the best way to deal with it."
Elsewhere, leaders Southampton moved four points clear of second placed West Ham, who face Cardiff on Sunday, as Rickie Lambert struck in the 16th minute to secure a 1-0 win at Leeds.
Birmingham drew 2-2 with Derby, Barnsley were held to a 1-1 draw by Nottingham Forest and Crystal Palace beat Peterborough 1-0.
Watford came from two goals down to beat Burnley 3-2 and Doncaster drew 1-1 with Brighton, while Leicester defeated Coventry 2-0.
Source: AFP
Source: AFP