"West Ham's need is even more pressing though, and they must start with the belief that they can follow last week's vital victory against Southampton with a first away to Chelsea for over 15 years". Replying strongly after the interval, Marcos Alonso was denied by Hugo Lloris in what would have been a deserved goal to return their advantage.
But Chelsea missed a host of chances to increase their advantage and were made to pay when Hernandez came off the bench to snatch the leveller with 17 minutes left.
The match is of high importance for Chelsea despite the race for top four being all but over for Antonio Conte's side, with them eight points behind Tottenham Hotspur with just seven games remaining.
The former England midfielder, who played for Chelsea for six years in the 1970s and had several spells as the club's assistant coach, was remembered by fans who laid flowers outside the stadium. While it has a lot to live up to surpass the excitement levels provided in Manchester, it's a game which both teams desperately need to win to restore some lost face.More news: Tour bus headed to the Masters golf tournament flips on Georgia highway
The half ended with the home side leading by a single goal.
Chelsea surrendered their leadership in the game when Javier Hernandez benefited from a precise pass from the right wing to put the ball right behind Thibaut Courtois' back in the 73rd minute.
His goal had goalkeeper Joe Hart, himself a star on Sunday, praising the diminutive striker for his desire following an global call-up on the other side of the ocean.
Described by many as the flawless gentleman, it was at Chelsea where he launched his senior career, scoring 30 goals from only 179 appearances in the Blues midfield.More news: Silver! Cyclists earn first Games medal for NZ
Here are the biggest winners and losers from this evening's match between the sides.
"They tell me last season he had very few injuries, but he picked up one at the end of the season with his hamstring and he's never really recovered from that".
The Brazilian has been Chelsea's best player this season and he deserves more than the Europa League next term.More news: March US job growth slower than expected