Last season's Champions League winners will bid to carry the momentum from a successful week into the Barclays Premier League clash after keeping alive their two remaining quests for silverware.
Chelsea fought back from two goals down to draw with Manchester United and force an FA Cup quarter-final replay, which - coupled with their progression to the Europa League quarter-finals, where Russians Rubin Kazan await - means Rafael Benitez's side face six games in 16 days.
The international break which follows Sunday's derby with the Hammers offers a pause for breath but first the Blues will seek to enhance their place in the top four as they bid to secure Champions League qualification.
"Three points are a must for us on Sunday - we need to win the match," Hazard, who scored in the Old Trafford fightback, said on Chelsea's official website.
"Chelsea are a big club - we have to win titles and to qualify for the Champions League. There's a lot to do but we'll try to do it all."
Hazard believes the close proximity of last night's 3-1 win over Steaua Bucharest, which secured a place in the Europa League last eight 3-2 on aggregate, could benefit Chelsea against a Hammers side who will be playing just their second match of the month.
"It might favour us at the start of the game because we should be able to set the tempo and get into our stride quicker because we've been more used to playing competitive games recently," Hazard said.
"But where it might favour them slightly is the fact that towards the end of the game tiredness may set in for us, while in effect they should be stronger because they've had a bit of a rest.
"It's something we have to deal with, and with the support of our fans behind us I'm sure we will be able to."
Chelsea suffered the first defeat of Benitez's tenure at Upton Park in December, despite entering half-time leading 1-0.
"At Upton Park, one or two errors crept in, particularly during the second half, but we were very good in the first half," Hazard said.
"We need to try to repeat that first-half display on Sunday and make sure we get a positive result. We are going into the game in good form, so we should be able to produce a strong performance."
There is no doubt Champions League qualification is a must for the Blues - the consequences of missing out could be great - and the fixture schedule is a challenge.
The first leg with Rubin Kazan, who beat Spain's Levante, follows two matches in three days - against Southampton in the Premier League and Manchester United in the FA Cup.
The second leg takes place three days prior to the crucial Premier League fixture at home to top-four rivals Tottenham.
The away fixture could take place in either Kazan or Moscow, with a decision to be made by UEFA shortly.
"From a geographical point of view we probably would have preferred a different draw," Hazard said. "We have to get through and playing in Russia is never an easy game.
"However, we have to make sure we do enough in the first leg to go over there and secure our place in the semi-finals."
If Chelsea reach the Europa League and FA Cup finals, the season will stretch to 70 matches, with Benitez already facing a challenge to best utilise a squad short on options.
Demba Ba is poised to return up front against the Hammers, even though Fernando Torres scored and missed a penalty against Steaua, while Frank Lampard was an unused substitute against the Romanians yet could be back against his former club as he seeks his 200th Chelsea goal.
Ramires, who could make way for Lampard, provided his backing for Benitez, who has been derided by many at Stamford Bridge due to his prior association with Liverpool.
"There's no time to celebrate - the games are coming one after the other," the Brazil midfielder said on www.uefa.com.
"Benitez is the coach and we have to do what he says because he wants the best for the team. There isn't anyone better than him to tell us what is best.
"The players try not to get involved in this issue. As long as he's here the players will seek to support him because he's our manager and we want to win."