These clubs find themselves at opposite ends of the Premiership. Portsmouth are trying to stave off relegation, and have lost four of six matches, including the last two. They've only been beyond the fourth round once since 1997. Two seasons ago, having knocked out Liverpool, they then faced Arsenal in the Quarter-finals at Fratton Road, and were totally outplayed, losing 1-5.
The South Coast side have only won the Cup once, but they held it for longer than anyone. They defeated Wolverhampton Wanderers 4-1 in the last pre-War final in 1939 and kept it until Derby beat Charlton in 1946. The attendance for the Pompey Cup Final triumph was 99,370.
Liverpool are six times winners and six times runners-up of the FA Cup, but have only made the last 16 once in the last four years, and that was the occasion when Portsmouth ended their run in the season before last. The Reds duly got past Luton in an extraordinary third round encounter when three goals in 11 second-half minutes rescued them in a breathtaking match of eight goals, covered live by BBC Match of the Day cameras - as is this Sunday evening game.
The European champions have lost only one of their last seven games and two of 19 in all competitions.
The Merseysiders went on to win the Cup in 1992 after eliminating Portsmouth in the Semis. They beat Sunderland (second tier) 2-0 in the Wembley Final with goals from Michael Thomas and Ian Rush. The Reds have made only one appearance since the Final has been staged away from Wembley. It was a victorious one, beating Arsenal 2-1 in 2001 in the first to be held at the Millennium Stadium. Gerard Houllier's Reds pulled the game out of the fire with two late strikes from Michael Owen.