Inexplicable mistakes by Joe Hart and Gareth Barry gave Manchester City's title hopes a potentially decisive blow at Southampton.
After defeat to Sunderland at St Mary's, Saints boss Nigel Adkins but described the team's performance as 'uncharacteristically flat'.
QPR & Southampton had conceded 49 goals between them prior to the game and the hosts' defence was breached 23 minutes - thanks to Lambert.
McDermott felt his side were not at their best until the second half.
"First half we were a little bit too respectful, in the second half I thought we deserved to win," he said.
"In any sport what you need to do is stay in the game, I just said (at half-time) that you are right in the game at 1-0 and if we can raise our tempo and play the way we can it will give us an opportunity.
Brian McDermott believes the club's maiden Barclays Premier League victory of the season is a turning point for the club. The win lifted Reading out of the bottom three. More details and all the latest football news can be found on the ITV Sport site here.
– Brian McDermott, Reading FC Manager - full coverage on the ITV Sport website here
Everyone was saying 'You haven't won, you haven't won' and that can play on people's minds and I obviously know that.
"But all you can do is concentrate on playing the game, enjoying the games and then the results will come because I know with the group we have got there was never any fear that they couldn't do it.
"Certainly as the manager it (the winless streak) is not relevant, all that is relevant is the points you have got on the board.
Football fans can keep up with all today's match action in the Premiership, Championship, Division One & Division Two via this link to the website. Or you can just follow your favourite team in the ITV Meridian directly through these links below with live updates as they happen.
- Liverpool v Reading
- West Ham v Southampton
- Brighton v Middlesbrough
- Bournemouth v Tranmere Rovers
- Hartlepool v Crawley Town
- Portsmouth v Shrewsbury Town
- Swindon v Scunthorpe
- Aldershot v Rotherham
- Gillingham v Burton Albion
- Oxford United v Accrington Stanley
All games are a 3 pm kick off.