London:Nottingham Forest stunned one of the world's wealthiest clubs by knocking Manchester City out of the FA Cup with a 3-0 third round win in front of the Premier League club's own fans.
Southend too shocked one of soccer's cash-rich teams in Chelsea by grabbing an injury-time equaliser in a 1-1 draw away to the Premier League's second-placed side.
Third-tier Hartlepool also ensured the third round stage lived up to its reputation for upsets with a 2-0 win over Premier League Stoke City.
FA Cup holders Portsmouth were held to a goalless draw at home to Bristol City while Premier League basement side West Brom could only manage a 1-1 draw with League One Peterborough.
Arsenal saw off Plymouth 3-1, with Robin van Persie scoring twice, while Premier League leaders Liverpool, in captain Steven Gerrard's first match since being charged with assault, won 2-0 away to Preston.
At Eastlands yesterday, Nottingham Forest, former European champions but now struggling in the second tier, struck twice before half-time to pile the pressure on City boss Mark Hughes, who was without injured Brazilian superstar Robinho.
Nathan Tyson's shot from outside the box put Forest ahead before Wales striker Robert Earnshaw scored to make it 2-0.
Forest's victory was completed 15 minutes from time when Joe Garner seized on a poor City throw-in to lash the ball past Joe Hart.
"When we play well and everyone shows the same desire, we are a good team," said Hughes. "But when we're off the pace then we're not.
"We need more players," added Hughes, making it clear he wanted to spend during the January transfer window.
Forest caretaker manager John Pemberton, who gives way to Billy Davies tomorrow said, "This is one of the highlights of my career."
Third tier Southend held out for over half an hour at Stamford Bridge, before falling behind when Salomon Kalou headed in a Frank Lampard corner.
However, they levelled in the 90th minute as Peter Clarke marked his 27th birthday with a goal.
"We need people to score more goals," Chelsea manager Luiz Felipe Scolari said after his first taste of FA Cup action. "The result says it was not a good performance but we had 15 chances to score a goal."
Southend boss Steve Tilson added: "We've had a good Cup run but I am more focused on our league game against Crewe now."
Albert Riera's put Liverpool ahead in the 25th minute at Deepdale with a fierce shot.
Preston thought they'd levelled late on through Sean St Ledger but his 'goal' was ruled out for a foul in the box by Jon Parkin on Liverpool defender Jamie Carragher.
Stoppage time then saw Fernando Torres score his first FA Cup goal after he was unselfishly played in by Gerrard.
"We always seem to have problems against lower league opposition," said Carragher.
"We only got the second goal in the last minute and we had a couple of late scares so great credit to Preston."
The day's all-Premier League clashes saw Hull and Newcastle play out a goalless draw while Sunderland gained revenge for their recent league defeat with a 2-1 win over Bolton.
Elsewhere, Middlesbrough were made to sweat by non-league Barrow before winning 2-1 and Fulham defeated Sheffield Wednesday by the same scoreline. Everton beat Macclesfield 1-0 while West Ham ran out 3-0 winners over Barnsley.
In a clash between two non-league sides, Kettering knocked out Eastwood Town, the lowest ranked team left, 2-1.
Forest Green, in the third round for the first time in their 118-year history, stunned managerless Derby through Jonathan Smith's 14th minute volley.
Derby, who play Manchester United in the semi-finals of the League Cup on Wednesday, then found themselves 2-0 down when Alex Lawless evaded the Rams defence to beat Roy Carroll at the near post.
Rob Hulse's 40th minute header saw Derby pull a goal back and on the stroke of half-time they were on level terms through Martin Albrechtsen.
However, Forest Green regained the lead 18 minutes from time through Paul Stonehouse only for the Rams to draw level a minute later through Paul Green.
And in the 87th minute Derby's revival was complete when Steve Davies scored from the penalty spot.
Second-half goals from Michael Nelson and David Foley secured managerless League One Hartlepool's passage into the fourth round at the expense of Stoke.
"It was a fantastic afternoon," said Chris Turner, Hartlepool's caretaker boss.
Stoke, in the top-flight relegation zone, rested seven first-team regulars - a clear indication of where manager Tony Pulis's priorities lay.