Wayne Rooney's stoppage-time penalty spared Manchester United from an embarrassing goalless draw as they edged third-tier Sheffield United 1-0 in the FA Cup third round on Saturday.
Holders Arsenal and Manchester City both had little trouble reaching round four, but United looked destined for an unwanted replay until Rooney struck in the 93rd minute after a foul on substitute Memphis Depay.
It was only the second shot on target that United had mustered, against a team 47 places below them in the English league system, and it is unlikely to save manager Louis van Gaal from criticism.
United's fans made their feelings plain with mocking applause whenever their team registered an effort at goal and Van Gaal was being loudly goaded by Sheffield United's fans until the late drama.
His side seemed to have turned a corner last weekend when they beat Swansea City 2-1 to end an eight-game winning run, but they looked desperately short of ideas on their return to Old Trafford.
It took them 69 minutes to hit the target, Matteo Darmian shooting tamely at George Long, but with injury time ebbing away, Dean Hammond was penalised for lunging in on Depay.
The United winger reacted with an exaggerated dive, but there had been contact and Rooney made no mistake by sending Long the wrong way from the spot.
Elsewhere, Aaron Ramsey and Olivier Giroud scored as Arsenal started their FA Cup defence by coming from behind to defeat Sunderland 3-1.
Sunderland took a 17th-minute lead at the Emirates Stadium through Jeremain Lens, but Joel Campbell equalised eight minutes later before second-half goals by Ramsey and Giroud gave Arsene Wenger's men victory.
"It was a test for us to come from behind. There was a great mental response and there is a special solidarity in the team," said Wenger, who has never lost a third-round tie. "I am very happy overall."
Manchester City won 3-0 at Norwich City, where Sergio Aguero, Kelechi Iheanacho and substitute Kevin De Bruyne scored their goals.
Southampton and Newcastle United both fell at the first hurdle, but could at least console themselves that they were beaten by fellow Premier League teams.
Wilfried Zaha's 68th-minute goal gave Crystal Palace a 2-1 win at Southampton, while Troy Deeney punished a loose back-pass from Georginio Wijnaldum to give Watford a 1-0 home victory over Newcastle.
West Bromwich Albion had James Morrison to thank for an equaliser in the fifth minute of stoppage time that prevented his side from losing at home to second-tier Bristol City.
After substitute Saido Berahino gave West Brom a 67th-minute lead, goals from Jonathan Kodjia and Kieran Agard put Bristol City in charge, only for Morrison to secure a 2-2 draw at the death.
Aston Villa's wretched season continued as they were taken to a replay by fourth-tier minnows Wycombe Wanderers following a 1-1 draw at Adams Park - their 16th successive game without victory.
Eleven points adrift of safety at the foot of the Premier League table, Villa took a 22nd-minute lead through Micah Richards, only for Joe Jacobsen to equalise with a penalty early in the second half.
Villa captain Richards went over to speak to frustrated Villa fans at the final whistle and manager Remi Garde said: "It was brave of him to do that.
"As professionals, we have to face our responsibilities - not only Micah, me and all the players."
Bolton Wanderers, bottom of the Championship and at risk of bankruptcy, narrowly escaped succumbing to the day's biggest shock as Darren Pratley's scrappy 87th-minute goal earned them a 1-1 draw at fifth-tier Eastleigh.
The lowest-ranked team left in the tournament, Eastleigh had gone ahead in the 51st minute via an own goal by Bolton's French defender Dorian Dervite.
"It's quite emotional. The players have put in an unbelievable performance and we probably deserved to win the game," Eastleigh manager Chris Todd told the BBC.
"But we're still in the draw for the fourth round, so we're happy overall."
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