Sunderland's midfielder Kieran Richardson (L) clashes with Arsenal's striker Alex Oxlade-Chamberlain
Arsenal's season of woe took another miserable turn on Saturday as the Premier League giants crashed out of the FA Cup in a 2-0 defeat at Sunderland.
Arsenal -- all but eliminated from the Champions League in midweek following a 4-0 rout by AC Milan -- saw their last realistic chance of ending a seven-year trophy drought snuffed out at the Stadium of Light.
Kieran Richardson took advantage of a poor clearance to lash in Sunderland's opener in the 40th minute before more shoddy Arsenal play culminated in a 77th-minute own goal from Alex Oxlade-Chamberlain.
The defeat means Arsene Wenger's side are left with only qualification for next season's Champions League to play for this term, and provides further ammunition for Arsene Wenger's growing legion of critics.
Wenger had uncharacteristically criticised his players in public following the Milan defeat and demanded a response against Sunderland.
However Wenger's men were always struggling to impose themselves as Martin O'Neill's advanced to the quarter-finals with an energetic display.
"I felt we were a bit unlucky. It was a 100 per cent performance from us and their first shot was a goal. Then we had to chase the game, take a gamble and they caught us on the break for the second goal," said Wenger.
"We had a lot of possession, but didn't create a lot of because of some fantastic defending by Sunderland."
Chelsea manager Andre Villas-Boas' problems mounted after his side laboured to a 1-1 draw with lower league Birmingham.
Daniel Sturridge headed home a second-half equaliser to save Chelsea's blushes at a restive Stamford Bridge after David Murphy had fired Birmingham into a shock lead on 20 minutes.
Villas-Boas' position has come under scrutiny following reports of a training ground mutiny by his senior players after last weekend's Premier League defeat against Everton at Goodison Park.
His team have now won just one game in their last six games across all competitions and Villas-Boas was forced to watch as his side were booed off the field following another unconvincing display.
"It is a poor result of course. We had a better performance in the second half compared to the first half," Villas-Boas said afterwards.
"1-1 is not what we expected, but it gives us another chance at Birmingham as we try to win a trophy," added Villas-Boas, who insisted he enjoyed "unconditional" support from Chelsea owner Roman Abramovich.
Elsewhere in the last 16, Championship side Leicester claimed a Premier League scalp as David Nugent's second half winner clinched a 2-1 victory at Norwich.
Nigel Pearson's team made the perfect start through Irish defender Sean St Ledger, who headed in Ben Marshall's corner in the fifth minute.
Norwich equalised in the 23rd minute when Leicester goalkeeper Kasper Schmeichel gave away a penalty with a foul on Elliott Bennett.
Schmeichel saved Wes Hoolahan's spot-kick, but couldn't prevent the midfielder scoring from the rebound.
However, Nugent gave Leicester victory when the former England striker latched onto Jermaine Beckford's flick and fired home in the 71st minute.
Japanese teenager Ryo Miyaichi inspired Bolton as the struggling Premier League side brushed aside Championship outfit Millwall 2-0 at The Den.
Owen Coyle's team, beaten semi-finalists last season, are second bottom of England's top flight, but they quickly took control in south London as on loan Arsenal midfielder Miyaichi marked his first Wanderers start by sweeping a high finish past Steve Mildenhall in the fourth minute.
Former Liverpool striker David Ngog ended Millwall's hopes of a replay when he claimed his third goal of the season with a powerful strike from just outside the penalty area in the 59th minute.
Everton took the express route into the last eight with a 2-0 win over Championship club Blackpool at Goodison Park.
It took only 49 seconds for David Moyes' side to take the lead through Dutch forward Royston Drenthe's emphatic finish and Argentine striker Denis Stracqualursi increased their advantage just five minutes later with a close-range finish.
Blackpool wasted a chance to reduce the deficit in the final minutes when veteran striker Kevin Phillips blasted a penalty over the bar.