The Belgian has also praised the role of Nemanja Matic in the side.
The Spanish pairing were signed by Jose Mourinho last summer as he sought to improve upon a third place finish for the Blues the year before, with them going on to win the Premier League comfortably in 2014/15.
Both players played key roles across the season, with Fabregas adding the vital assists the side had been missing, while Costa proved to be the goalscorer they had sorely missed in previous campaigns.
Now Hazard has praised the duo for their influence on the side, and himself in particular.
“When you play with big players you feel better,” he said.
“With Diego, you know you don’t always need to get so far forward because he is always there; you just have to try to create something for him. Cesc is the same; you just have to connect with him when he has the ball, so it’s always good to play with big players. We have a lot of big players in our team.”
The Belgian winger was Chelsea’s star man last season as he won both the PFA and Football Writers' Player of the Year awards, while he was arguably the star performer in the entire Premier League.
For Hazard to be so devastating up front, however, he had to rely heavily on an impressive defence, led by John Terry. For him, though, there was one player who was just as important to the collective cause, and that was Nemanja Matic.
“I also think Nemanja is very important for the team,” he added.
“I know when I play with him I can focus more on the attacking part of my game because he is always behind me. If I can’t get back at a certain time, he is there to cover.”