Leeds, currently top of League One (division three) but Liverpool's equals for decades until their relegation from the top flight five years ago, succumbed to a superbly executed 66th minute goal scored by 20-year-old French striker David Ngog who span and sidefooted past Leeds keeper Shane Higgs.
"I have to be patient because I know I can't play in every game," he told Sky Sports, "but I know the manager has confidence in me and I was delighted to score."
Leeds had plenty of chances to score and thought they had taken the lead when Jermaine Beckford's first-half effort was touched over the line by Luciano Beccio, but the goal was disallowed by a controversial offside call by the linesman.
Old memories were also being revived at the Britannia Stadium where Stoke City and Blackpool, the two clubs Stanley Matthews played for between 1932 and 1965, fought out a seven-goal thriller, with Premier League Stoke winning 4-3 after Andy Griffin's winner six minutes into stoppage time.
Blackpool led 2-0 with goals on either side of halftime from David Vaughan and Billy Clarke, before Stoke hit back to lead with three goals in three minutes from Danny Higginbotham, Matthew Etherington and Ricardo Fuller before Blackpool made it 3-3 with nine minutes to play.
However with extra time looming, Griffin scored Stoke's winner with a solo effort. Liam Lawrence also missed a penalty in the second half for the home side.
While Blackpool lost their chance of a Premier League scalp, Championship (second division) side Barnsley claimed one when they beat last season's semi-finalists Burnley 3-2 at Oakwell with Argentine defender Hugo Colace scoring the 75th minute decider.
Arsenal, fielding eight teenagers, beat Championship leaders West Bromwich Albion 2-0 at home with 18-year-old London-born striker Sanchez Watt opening the scoring on his debut and Carlos Vela adding the other. West Brom's cause was not helped when former Arsenal trainee Jerome Thomas was sent off in the first half.
Portsmouth, bottom of the Premier League, won 3-1 at League One (third division) Carlisle United but had to come from behind before advancing to the last 16 and Saturday's fourth round draw.
In an all-Premier League match Sunderland were 2-0 winners over Birmingham City while Blackburn Rovers won 1-0 at Championship side Nottingham Forest.
Bolton beat West Ham United 3-1 after extra time at the Reebok Stadium, while Peterborough also scored a memorable win with a 2-0 victory over Newcastle United.
The third round will be completed on Wednesday when holders Manchester United face Wolverhampton Wanderers at Old Trafford in one of the six remaining ties.
(Editing by Justin Palmer)