Hernandez and Arnautovic were both on target as the Hammers gave their survival hopes a major shot in the arm with a 2-0 win over Watford.
Mexico striker Hernandez headed his third goal in four Premier League games before half-time, and Austrian playmaker Arnautovic capped an all-action performance with the second 12 minutes from the end.
“Marko is an unbelievable, all-around player and it gives you a lot of confidence when you play up front with a player like him,” Hernandez told the club website.
“We have a good understanding with each other and both of us scored. That’s a good thing for a striker.
“Not only did we score, but the whole team ran with high intensity and we showed that we wanted the three points.
“Three points are three points whoever they come against, and we need to keep going day-by-day and game-by-game because every game is going to be a final.”
These two… pic.twitter.com/En2JVlQGr7
— West Ham United (@WestHamUtd) February 10, 2018
The duo now have seven goals apiece this season, with West Ham’s latest victory moving them up to 30 points, level with Watford.
Meanwhile, Hornets striker Stefano Okaka was not in their squad despite not being injured. Okaka had looked set to leave Vicarage Road before the transfer deadline with Fulham, Malaga and Galatasaray all linked, but a move did not materialise.
Yet he was not involved at the London Stadium despite boss Javi Gracia having only 17 senior players available.
“It’s another situation,” said Gracia. “This week he was out of training, he was out of the team. Maybe next week he will be with us, but at this moment I can’t say anything else.”
Aguero’s quadruple – incorporating his third hat-trick of the season – took his total for the campaign to 28 and his overall City tally to 197.
But as impressive as the Argentinian was, City again owed a lot to the irrepressible De Bruyne, who created his side’s opening three goals in another outstanding display.
“Luckily Kevin De Bruyne is playing for us and helping us to score,” said Aguero, who with 143 Premier League strikes is now only three short of moving into the competition’s top 10.
“I am very lucky because most of the goals come from his assists – I just have to hit the ball. I am happy for him as well. He is a great player and any team in the world would love to have him.”
Most of the pre-match headlines were made by Leicester winger Riyad Mahrez, who was back on the bench after ending more than a week of self-imposed exile following the collapse of a move to City.
But the Algerian could only watch as City raced out of the blocks.
The hosts took a third-minute lead through Sterling, the England international turning home a De Bruyne cross from close range to exorcise the memory of a miss from similar distance at Burnley the previous week.
The Foxes replied with a breakaway goal from Vardy but City took a grip as Aguero struck twice in quick succession after half-time. Leicester sent on Mahrez but to no avail, with Aguero netting twice more.
It was a good way to sign off from Premier League action for the month, with City having Champions League, FA Cup and Carabao Cup commitments in the next fortnight.
“The goals are very important because they help the team to win,” said Aguero. “But I think we are very close to achieving important things. That is why I am very happy, personally and for the team.”
Leicester boss Claude Puel, who insisted Mahrez had been welcomed back into the group, admitted his side were outplayed.
“They had more confidence, found more quality and took the space,” the Frenchman said. “We played against a good team and a fantastic striker in Sergio Aguero. He scored four fantastic goals.
“It is tough for us to concede five goals – it was a big disappointment – but we were a little lucky to come back in the first half and be on level terms.
“The second goal made it too difficult for us because they have the quality to play between our lines and recover the ball quickly, with strong pressing. It was too difficult for us to resist.”
Salah has been in stunning form since his summer switch from Roma, scoring 21 goals in the Premier League to inspire the Reds’ push for a top-four spot.
The 25-year-old’s performances have even seen him linked with La Liga giants Real Madrid, however, Eto’o believes the Egypt icon is a future Liverpool captain.
“He has probably been one of the best players in the world,” Eto’o said.
“His performances for Liverpool have been great and, for me, I am always glad to see African players at the top level.
“He deserves his awards and hopefully he has more years like this.
“He will not scream at you to do this or do that but people like him command respect.
“His attitude off the pitch also makes him a natural leader. He can grow into the captain there.”
Salah is likely to take his place on Liverpool’s right side once again as they travel to Southampton on Sunday with Jurgen Klopp’s men looking to consolidate their place in the top four ahead of Wednesday’s Champions League last-16 trip to FC Porto.