Manchester United and Liverpool have traditionally battled for supremacy in English football.
Liverpool's golden period, starting in the mid-1970s and spanning the 1980s, gave way to Alex Ferguson's dominant reign at Old Trafford, when United usurped its rivals' tally of 18 top-flight titles.
As such, the Merseyside club have generally played second fiddle during the Premier League era – but that might all be about to change with Jurgen Klopp at the helm.
United has never been further behind Liverpool in the Premier League before Christmas than the yawning 16-point deficit it will aim to make a dent in at Anfield on Sunday.
Here, we look back at some other moments when this battle has been fought on uneven terms.
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United on the eve of a golden era
Jose Mourinho's track record as a proven winner was supposed to provide the antidote to the fallow post-Ferguson years at United.
While that has not yet proved to be the case, the under-fire Portuguese can perhaps find consolation in the fact that the last United boss to find himself 16 points behind Liverpool in December was Alex Ferguson.
The redoubtable Scot would hardly have been feeling festive on Christmas Eve 1990 as United sat in seventh on 28 points, looking up at Division One leaders Liverpool on 44.
The Reds were reigning champions and on track to add a 19th title. But Kenny Dalglish stood down the following February, George Graham's Arsenal finished in top spot and Liverpool began a wait that continues to this day.
United improved marginally to finish sixth – 17 points behind Liverpool – and was runner up to Leeds United the following season before lifting the inaugural Premier League in 1992-93.
Leaving the perch
When Ferguson's United made it back-to-back titles in 1993-94, Liverpool was 32 points worse off in eighth position.
It proved to be a chastening two decades, with the 2001-02 campaign under Gerard Houllier the only time Liverpool finished ahead of United. It was second behind Arsenal on 80 points, with the third-placed Red Devils on 77.
The biggest difference came in 2011-12, when United missed out on the title to Manchester City on goal difference but was still 37 points better off than Liverpool in eighth.
Indeed, during Ferguson's final four campaigns at the helm, Liverpool was never within 22 points in the final reckoning.
Going close under Rodgers
It meant the 2013-14 season was something of a culture shock for all concerned. United began a new era under David Moyes that it swiftly decided was a mistake. Following the Scot's sacking it limped to seventh place.
Brendan Rodgers brought Liverpool to the edge of glory, only for City to seal its second Premier League in three years on the final day.
Liverpool finished 20 points ahead of United – its strongest position in the rivalry for a generation, while a 3-0 win at Old Trafford in March 2014 showed the kind of gulf in glass some in Manchester fear might be exposed this Sunday.
In three of the subsequent four seasons, United ended up back above Liverpool. One of the challenges for Klopp and his undefeated title-chaser is to turn this advantage into something more permanent.