The first game in a three-game set at St James’ Park on Saturday night is a vital one.
The first of a series of away games at the home of Chelsea is the biggest one of the season, and it will decide who the Blues win or lose.
If they come away from this fixture with the best possible record, it would give them a two-point cushion in the race for a top-four finish.
If, however, they lose the game, they would fall back down the table and face an uphill battle against relegation.
A win would give the Blues a home advantage of four points, but a draw would drop them to seventh and risk a return to the bottom of the table.
This would also see a return of the three-goal rule which has been in place since the season started.
If the Blues lose the second game, which would give Chelsea a two point cushion in this match, they face the prospect of losing their Europa League spot if they finish in sixth.
This, coupled with the fact that they will not face Manchester United in the FA Cup final, means that a win for Chelsea would make them a realistic possibility of avoiding a relegation battle for the first time in four years.
If Chelsea win and Manchester United lose, the tie would be decided by a goalless draw.
If neither side win or draw, Chelsea will have to play Manchester United at home for a sixth game, while the remaining two fixtures are played away from home.
This will give Chelsea the chance to build a two game winning streak into the first leg, which is important given the way they played at Stamford Bridge last week.
They will face Manchester City on Tuesday night in the Champions League first leg.
The Blues have the potential to have their best home record in Europe for a long time, and with a strong home record, they should be able to put a decent second leg of the Premier League season behind them.
They have only lost once in their last 13 games away from Stamford Bridge, against Norwich in the Capital One Cup semi-final last week, so there are plenty of positives to take from that game.
This has been the best away start in the Premier Leagues history, and there are a lot of positives for Chelsea.
Chelsea have played the majority of their games at Stamford Hill and it has been an ideal opportunity for the club to get used to playing away from the club’s home ground.
The visitors are a solid team who play a solid brand of football, and the Blues have not had too many issues with their own goal scoring in recent weeks.
With the home-field advantage in hand, Chelsea are in a good position to win this game.
If Manchester United manage to win the first game, the Blues would then have a huge advantage in the tie.
The second leg is played at St. James’ Stadium, a ground where they have a long-standing history, with the home side having won nine of the last 10 games at home.
If United win this tie, they will have a much better chance of staying in the top four of the league.
They would then face Manchester Utd, the second team in the Europa League.
If this match ends in a draw, they have two more games left to play before they face Bayern Munich in the final.
They are currently ninth in the table, but if they are able to secure the top spot they could be looking at a much tougher trip to Bayern in the first half of the next season.
This could mean a return home to the Emirates Stadium in the summer, where they are currently playing a game in the third tier of English football.
Chelsea should be confident in their ability to win against Bayern, as they have won eight of their last nine away matches at home this season.
They should also be able put their game against Bayern in perspective and be confident of their chances of reaching the final at Stamford Hills.
However, if they fail to do so, they are in danger of being relegated.
This season, Chelsea have finished third, behind Manchester United and Tottenham Hotspur.
They lost to Tottenham in the opening round of the FA Premier League, and a draw against Manchester City in the semi-finals.
This means that they have only won one of their five matches at the Allianz Arena this season, which could put a real dent in their hopes of staying up for the Champions Leagues.
If there are no results from the remaining fixtures in this tie then the tie will decide whether Chelsea finish in the bottom four or in the drop zone.
If either side of the tie are able on Sunday to win and finish fourth or lower, they could face a tricky run to the play-offs.
They face Arsenal on Saturday and Manchester City the following weekend.
Chelsea will need to be confident at Stamford Gate in order to avoid relegation, and they will be hoping that a successful start to the season will do the trick.
If Mourinho is not at his best, the pressure will be on him