Humble Barnsley produced a sensation on Saturday beating Liverpool 2-1.
Humble Barnsley produced an FA Cup sensation on Saturday when they came from behind to beat Liverpool 2-1 with virtually the last kick of the game to advance to the last eight in dramatic style.
Brian Howard's 20-yard strike, moments after the Yorkshire club had had a penalty appeal turned down at Liverpool's Anfield home, sealed a memorable victory for the Championship side and added to the pressure on under-fire Reds boss Rafael Benitez, who controversially left out several key players.
Meanwhile Manchester United, last season's losing finalists, surprisingly thrashed Premier League leaders Arsenal 4-0, the Gunners playing most of the second-half with to 10 men after Emmanuel Eboue was sent-off.
The Old Trafford match was effectively over before half-time as United, five points behind Arsenal in the league table, stormed into a three-goal lead thanks to Wayne Rooney, Darren Fletcher, who scored again after half-time, and Nani.
At Anfield, Liverpool, who twice fell behind at home to non-league Havant and Waterlooville in the last round, were left having to rebuild their already fragile morale ahead of Tuesday's Champions League clash with Italian giants Inter Milan.
"We are throwing away games because we cannot take our chances and finish matches," said a frustrated Benitez.
"I'm really disappointed. They scored in the last minute. Sometimes this is football, this is the Cup. The only thing we can do now is prepare for the next game. We know it's an important match so we must keep our heads up."
Barnsley boss Simon Davey was delighted by his team's attitude.
"The players have been fantastic. I always felt we were in the game. We kept going right until the end and scored two great goals," he said.
Liverpool, the five-time European champions, didn't go ahead until the 32nd minute when striker Dirk Kuyt poked in a cross from fellow Dutchman Ryan Babel.
But Barnsley were level before the hour mark when Stephen Foster headed in a cross from Martin Devaney.
Australia's Harry Kewell almost wrapped up the tie for Liverpool when his shot hit the crossbar.
Goalkeeper Luke Steele, who only arrived on loan from West Brom on Thursday, had a Barnsley debut to remember with several fine saves before Howard struck.
At Old Trafford, England striker Rooney put United in front with a 16th minute header in a match where both the Premier League champions and Arsenal were resting key players ahead of midweek Champions League clashes.
Four minutes later midfielder Fletcher flicked in a header as he jumped alongside Arsenal defender William Gallas and Portuguese forward Nani then made it 3-0 with a well-taken shot.
Arsenal's plight was made worse when Eboue was sent-off for a studs-up jump into United defender Patrice Evra four minutes after the break before Fletcher scored his second header in the 74th minute.
In the day's other fifth round ties, holders Chelsea beat Huddersfield 3-1 while League One Bristol Rovers were the lowest-ranked team left in the Cup after a 1-0 win at home to Championship side Southampton saw them into the quarter-finals for the first time in 50 years.
Also through to Monday's draw were Cardiff City, who beat fellow Championship side Wolves 2-0, as they reached the last eight for the first time since becoming the only non-English club to win the FA Cup in 1927.
In Saturday's other all-Championship fifth round clash West Browmich Albion beat 10-man Coventry City 5-0.
Frank Lampard put Chelsea ahead at Stamford Bridge with an 18th-minute shot - the England midfielder's 100th goal for the Blues.
But Huddersfield, who knocked out Premier League Birmingham in the third round, shocked the crowd just moments before half-time when Michael Collins struck from 12 yards.
Lampard then settled Chelsea's nerves in the 60th minute when, after his shot was blocked by Huddersfield keeper Matt Glenon, he followed up to score from the rebound before Salomon Kalou put the result beyond doubt.
Rickie Lambert's deflected free-kick six minutes from time was good enough for Bristol Rovers to see off Southampton.
Premier League Portsmouth are away to Championship strugglers Preston on Sunday while the day's other fifth round tie sees Pompey's top-flight rivals Middlesbrough travel to Sheffield United.