Tottenham Hotspur needed a Lucas Moura equaliser to avoid an FA Cup third-round defeat at second tier Middlesbrough as Jose Mourinho's stuttering side emerged with a 1-1 draw on Sunday.
The eight-times champions trailed to Ashley Fletcher's fine finish just after the break but Moura's header spared a Tottenham side who were without injured striker Harry Kane.
Tottenham dominated following Moura's equaliser but Boro keeper Tomas Mejias, making his first start of the season, frustrated them with several saves as Boro earned a replay.
While Tottenham are in the last 16 of the Champions League, the FA Cup would appear to be their more realistic route to a trophy this season, but they flirted with defeat before Moura rose to head in Serge Aurier's superb cross in the 61st minute.
Mourinho, who has only won the FA Cup once, with Chelsea in 2006, cut a frustrated figure at times, especially when his side conceded a soft opener as Fletcher ran through all alone on to a long ball to beat Paulo Gazzaniga with a cool finish.
Troy Parrott was on the bench but did not feature.
Chelsea made nine changes to their starting line-up but beat Championship promotion hopefuls Nottingham Forest 2-0 with goals from Callum Hudson-Odoi and Ross Barkley.
Liverpool midfielder Curtis Jones piled more Merseyside derby misery on Everton with a stunning second-half winner in the FA Cup third round.
Teenager Jones, at 18 years and 340 days, became the youngest goalscorer in the fixture since Robbie Fowler in 1994 by superbly curling home off the underside of the crossbar to earn a 1-0 success.
Everton have failed to win on their last 23 visits to Anfield, a woeful run stretching back to September 1999.
The defeat for Carlo Ancelotti's men was particularly embarrassing given they fielded a virtually full-strength side against an inexperienced Liverpool line-up which included nine changes and two debutants.
Former Manchester United and England striker Wayne Rooney helped Championship side Derby County spring a surprise with a 1-0 victory at Premier League Crystal Palace.
Former Palace loanee Chris Martin scored the only goal at Selhurst Park, while Michael Oliver made VAR history by becoming the first referee to use a pitchside monitor in England before deciding to send off Luka Milivojevic.
Oliver upgraded a booking for Eagles captain Milivojevic to a red card after watching a replay of an incident involving Rams midfielder Tom Huddlestone.
Top-flight Sheffield United were made to work hard by minor league outfit AFC Fylde, winning 2-1.
Wilder, who made 11 changes, saw his team go out of the competition at this stage last season as National League Barnet caused an upset at Bramall Lane.
The Blades hosted opposition from the same division again but this time avoided a giant-killing thanks to Republic of Ireland international Callum Robinson's early goal and a Leon Clarke strike on the hour.
However, the lowest-ranked team remaining in the competition made the Premier League club sweat by setting up a tense finale when Jordan Williams pulled a goal back with 12 minutes left.
Pablo Zabaleta was West Ham's unlikely saviour as they battled past League One Gillingham, who featured Southampton loanee and Republic of Ireland U21 defender Thomas O'Connor.
34-year-old Zabaleta, only on the field as a substitute after an injury to Ryan Fredericks, scored his first goal in almost three years to break the deadlock midway through the second half.
Then, as Gillingham chased an equaliser, fellow sub Pablo Fornals finished them off with a breakaway goal in stoppage time to seal a 2-0 win.
QPR thrashed fellow Championship side Swansea 5-1.
Jordan Hugill's double, plus goals from Bright Osayi- Samuel, Lee Wallace and Josh Scowen did the damage for the Hoops, while substitute George Byers netted the Swans' consolation at Loftus Road.
Elsewhere, League Two Northampton upset Burton with a 4-2 win at the Pirelli Stadium. Nicky Adams, Ryan Watson, Charlie Goode and Sam Hoskins were on target for the Cobblers, with Ryan Edwards and Scott Fraser scoring for the League One hosts.
Bristol Rovers centre-back Tony Craig scored for both teams in a 2-2 draw against League One rivals Coventry at the Memorial Stadium. Rovers led through Jonson Clarke-Harris' early penalty before Liam Walsh claimed the visitors' first equaliser.
In another all-Championship clash, West Bromwich Albion and Charlton Athletic made a combined 20 changes, with Albion winning 1-0 thanks to Kenneth Zohore's goal.
Second-half strikes from Conor Chaplin and Luke Thomas saw Barnsley beat Crewe 3-1 after Alex midfielder and former Ireland international Paul Green had cancelled out Jacob Brown's opener.