Liverpool let a 2-0 lead slip as League One Shrewsbury earned a FA Cup fourth round replay at Anfield thanks to a 2-2 draw, whilst Manchester United and Manchester City cruised into the fifth round on Sunday.
Jurgen Klopp showed Liverpool's focus is very much on a first Premier League title for 30 years as he made 11 changes to the side that won at Wolves on Thursday.
However, unlike against Everton in the third round, the German's gamble did not pay off despite a calm finish from 18-year-old Curtis Jones to open the scoring on 15 minutes.
Shrewsbury missed a host of chances to level before the break and seemed set to pay a heavy price when a freak own goal from Donald Love doubled the visitors' lead a minute into the second half.
The Shrews, though, did not give up on their shot at shocking the European champions and were given a lifeline when Yasser Larouci brought down Josh Laurent and substitute Jason Cummings scored from the spot.
Cummings then sent New Meadow into raptures by slotting low under Adrian 15 minutes from time.
A visibly furious Klopp threw on Mohamed Salah and Roberto Firmino from the bench in an attempt to avoid adding a replay to their congested schedule.
But it was to no avail as a draw will see his side's two-week winter break from Premier League action at the start of February shortened by a few days.
United boss Ole Gunnar Solskjaer was badly in need of a convincing performance after 2-0 defeats to Liverpool and Burnley over the past seven days and got a response with a 6-0 thrashing of third-tier Tranmere.
Many tipped the Red Devils to get bogged down on a sandy surface at Prenton Park, but a flying start thanks to a host of unlikely goalscorers ensured there was no chance of an upset.
"This game was one where everyone apart from Man United fans wanted us to lose," said Solskjaer.
"It's been a bit of pressure on them but they've enjoyed it.
"It was a difficult pitch but we went about it the right way; just worked hard, played simple but effective and played the right way."
Captain Harry Maguire led by example by striding forward to smash home his first goal for the club since an £80 million ($105 million) move from Leicester.
Diogo Dalot then also grabbed his first United goal before Jesse Lingard curled home for just a second time in a year for club and country inside 16 minutes.
Phil Jones nodded home his first United effort since 2014 and Anthony Martial's deflected strike made it five before the break.
Solskjaer could then afford the luxury of resting Martial, Maguire and Nemanja Matic for most of the second half ahead of Wednesday's attempt to overturn a 3-1 first leg deficit against City in the League Cup semi-finals.
Tahith Chong was one of those introduced and he was brought down by Tranmere goalkeeper Scott Davies, allowing Mason Greenwood to score United's sixth from the penalty spot.
City manager Pep Guardiola hopes more fans show up at the Etihad Stadium for the derby in midweek after questioning why there were 15,000 empty seats for his side's 4-0 stroll past Fulham.
Nearly 40,000 were in attendance to see Tim Ream's sixth-minute red card give the Championship side a mountain to climb after he hauled down Gabriel Jesus inside the box.
Ilkay Gundogan converted the resulting penalty before Bernardo Silva's smart turn and shot quickly doubled City's advantage.
The visitors then held out for nearly an hour but two headers in three minutes from Jesus gave the scoreline a more accurate reflection of the English champions' dominance.
"Hopefully more people can come than today, hopefully (they) can support us more," said Guardiola.
"I don't know the reason why, but it was not full."