Third tier Peterborough United produced the performance of football's FA Cup fourth round when they twice battled from behind in the dying minutes to earn a 2-2 draw at Premier League side West Bromwich Albion.
On a day when the big guns largely extinguished the hopes of the dreaming underdogs, the League One side proved indomitable after Saido Berahino, given a rare start, had twice put Albion ahead at the Hawthorns.
Peterborough's heroes were Shaquile Coulthirst, who equalised Berahino's first half goal in the 79th minute, and Jon Taylor, who then answered what had looked to be a late, late winner from the Albion striker with just four minutes left to earn his side a lucrative replay at their London Road home.
Portsmouth, who plunged into the fourth tier of the English game after financial woes, sniffed a sensation at a frantic Fratton Park before Premier League Bournemouth battled from behind to win 2-1.
The 2008 winners, now a supporter-owned club, had rekindled memories of the days when they used to be Bournemouth's south coast masters as they went ahead through their 31-year-old journeyman winger, Gary Roberts, just before halftime.
But Bournemouth belatedly flexed their muscles, substitute Josh King earning a 71st minute equaliser before Marc Pugh ruined the party with an 83rd minute winner.
Arsenal maintained their push towards winning the Cup for a third successive year as Alexis Sanchez, back in the starting line-up for the first time since November after injury, scored the winner in a 2-1 victory over Championship side Burnley at the Emirates Stadium.
The second tier side had provided some resistance after England defender Calum Chambers had put the Gunners ahead with Sam Vokes powering home a headed equaliser.
After the break, though, the class of Sanchez told as he swept home a cross to ensure Arsenal are still on course to emulate the back-to-back trebles of Blackburn Rovers and Wanderers back in the Victorian era.
Arsenal manager Arsene Wenger, protecting his record of only losing to a lower-league team once in 41 FA Cup ties, was happy to overcome what he felt was tough opposition.
"Burnley are a good side. When they equalised suddenly you could see, energy, commitment, and we had to dig deep to win the game," he told the BBC.
Liverpool's pursuit of a second Wembley Cup final appearance stalled at Anfield as Juergen Klopp's second-string side had to settle for an undistinguished goalless draw with West Ham United.
Four days after reaching the League Cup final with their penalty shootout win over Stoke City, Klopp, no fan of English football's congested fixture lists, opted to trust his youngsters as he made 10 changes to the team that played 120 minutes on Wednesday.
His faith was only partially rewarded with his young side creating enough chances to earn victory after a dour first half but lacking the cutting edge up front to avoid yet another fixture, an unwanted and difficult replay at Upton Park.
West Ham were, though, indebted to their goalkeeper Darren Randolph, who made fine stops from Cameron Brannagan, Joao Teixeira and Christian Benteke.
Some of the other favourites also booked their fifth round ties with some comfort.
Manchester City piled further misery on struggling Aston Villa with a 4-0 win, adorned by a hat-trick from teenage prospect Kelechi Iheanacho.
Villa's hopes of some blessed relief from their Premier League woes were swiftly extinguished when the 19-year-old Nigerian put City ahead after just four minutes at Villa Park.
Iheanacho then doubled City's lead, converting coolly from the penalty spot. Raheem Sterling, who had earned the penalty, had stepped up to take the kick but captain Pablo Zabaleta asked the youngster to do the duties.
He completed his treble after latching on Micah Richards' poor back pass before Sterling completed the rout with City's fourth.
"Kelechi is a very good young player," City manager Manuel Pellegrini told the BBC. "We let (Stevan) Jovetic and (Edin) Dzeko go because I see Kelechi every day and know what he can do."
Tottenham Hotspur took no chances, fielding a strong side as they accounted for League One Colchester United 4-1, featuring a double from Belgian Nacer Chadli.
Oxford United's hopes of another giant-killing act following their third round slaying of Swansea City were ended brutally with a comprehensive 3-0 defeat at home to Championship Blackburn Rovers.
The prolific Odion Ighalo came off the bench to strike in the 89th minute and steer Premier League Watford to a hard-fought 1-0 win at Championship Nottingham Forest.
There was a notable triumph for struggling League One outfit Shrewsbury Town with Jack Grimmer scoring their injury-time winner in a 3-2 win over Championship side Sheffield Wednesday.
In an all-Premier League clash, Crystal Palace beat Stoke City 1-0 with a splendid individual effort from Wilfried Zaha.