Liverpool face arch-rivals Manchester United for the first time in European competition on Thursday.
Here Press Association Sport looks at some of the issues ahead of their Europa League last-16 first leg.
WHO WILL CONQUER THEIR INCONSISTENCIES?
Liverpool go into the match after back-to-back wins but that is no guarantee of success as too many times this season they have shot themselves in the foot just when it seemed they had turned a corner. Similarly United won four in a row, admittedly two were against Shrewsbury and Midtjylland, before surprisingly getting beaten at West Brom - which is also characteristic of their season. The result is likely to be decided on who makes the fewest mistakes.
HOW HAS LOUIS VAN GAAL ACQUIRED THE INDIAN SIGN OVER LIVERPOOL?
The Dutchman has won all four games against the Reds since taking over at Old Trafford and Liverpool have never lost five in a row against their old enemies. But a closer look at those wins shows Van Gaal has enjoyed his fair share of luck, from Liverpool - mainly Raheem Sterling - missing a host of chances in his first encounter, through Steven Gerrard getting sent off seconds after coming on to Wayne Rooney nicking a 1-0 in at Anfield in January despite being second best.
DO VAN GAAL'S TACTICS MEAN THE KEY WILL BE HOW UNITED'S DEFENCE PERFORMS AGAINST LIVERPOOL'S ATTACK?
United have kept three clean sheets in seven encounters against fellow big-five opponents (Liverpool, Manchester City, Chelsea and Arsenal) this season, winning three and losing just once. They have managed to score just eight goals and six of those came in two games against Liverpool and Arsenal. Liverpool have scored 16 times in eight meetings against big-five teams - and first-choice striker Daniel Sturridge has played in just one of those.
SO WHO DOES HAVE THE BEST ATTACK?
United's top four scorers have 39 goals between them but 14-goal Wayne Rooney is out injured, although Marcus Rashford's emergence has given them a timely boost. Liverpool's best four have 30, evenly spread between them, and crucially all are fit. That quartet does not include Sturridge, who has scored five times in 11 appearances this season at a far greater strike rate than any of his team-mates.
WHAT ROLE CAN THE FANS PLAY?
There have been very few of those famous European nights at Anfield recently but on their day the supporters have more than played their part - just ask Chelsea about the wall of sound they faced during the 2005 Champions League semi-final. Long-serving matchgoers to both Anfield and Old Trafford have both complained about how the influx of 'tourists' has watered down the atmospheres and the teams' fortunes on the pitch have contributed to that but a midweek match under the lights should get the juices flowing again.