Manchester United against Liverpool is always a red letter day in the Premier League but Sunday's encounter at Old Trafford could be make-or-break for both of these two proud clubs.
Liverpool will be desperate to put a spoke in United's title charge as Sir Alex Ferguson's side bear down on their 19th league title.
The two teams are currently locked together on 18 Championships but, whereas United have won 11 of the last 17 titles, Liverpool's last success was 20 years ago.
However, Rafa Benitez's side have had an uncanny knack of shocking United in the last few years, most notably 12 months ago when they came from behind to win 4-1 at Old Trafford, although that only proved to be a blip as Ferguson's team went on to win their third successive title.
Victory for the Red Devils would boost their hopes of a fourth successive league crown, while Liverpool know that defeat could well spell the end of their pursuit of fourth place and next season's Champions League.
Meanwhile, Chelsea's minds are now focused on domestic matters following another Champions League failure.
The manager might have changed from Jose Mourinho to Luiz Felipe Scolari, Avram Grant and now Carlo Ancelotti but the outcome was depressingly familiar for the Stamford Bridge faithful.
It was Mourinho who returned to rub salt into the wounds as his Internazionale side ran out 1-0 winners in the second leg of their last-16 tie to triumph 3-1 on aggregate.
Afterwards a downbeat Ancelotti admitted the league and wrestling the title away from United's clutches is now their number one target for the remainder of the season.
Therefore the wounded Blues will be hoping that Blackburn Rovers are already starting to think about their summer holidays when they visit Ewood Park on Sunday.
Sam Allardyce's team have little to play for in the last nine matches of the campaign as they are ten points clear of the relegation zone and have no chance of clinching a place in Europe.
Despite their European struggles, Chelsea remains favourites with the sportsbooks to win the Premier League this season.
Before either of the two title rivals kick-off on Sunday, United are two points better off than Chelsea but have played one game more than the London club.
In the day's final encounter, Fulham entertain Manchester City at Craven Cottage.
Fatigue could be Fulham's biggest problem as they attempt to halt City's push to secure a place in next season's Champions League.
The Cottagers have played Juventus twice in the last week, with a Premier League game at Manchester United in between, while an FA Cup sixth-round replay at Tottenham is also on the horizon.
City, without ever really looking majestic under Italian coach Roberto Mancini, remain well placed to clinch the much-coveted fourth spot with an unlikely 4-2 victory at Chelsea and last-gasp equaliser at Sunderland last weekend keeping them on track.