Liam Rosenior labelled Chelsea's London derby against West Ham on Saturday as their biggest game of the season, saying he would "find out so much" about his players.
Rosenior, who replaced Enzo Maresca as Chelsea boss earlier this month, has enjoyed a strong start to his career at Stamford Bridge, winning his past four matches across all competitions.
The fifth-placed Blues are just one point behind fourth-placed Manchester United in the Premier League.
They maintained Rosenior's impressive run by securing a Champions League last-16 berth with a come-from-behind victory at Napoli on Wednesday.
Chelsea also have a chance to reach the League Cup final when they look to overturn a 3-2 deficit in the semifinal second leg at Arsenal on Tuesday.
Before that showdown, Rosenior's team host resurgent West Ham, who are still in the relegation zone despite successive wins.
"For me, tomorrow is the biggest game of the season," Rosenior told reporters on Friday.
"It's very simple, I'm going to find out so much. We're in a good place. If you want to be a consistent winning team, these are the games where you have to step forward and not be complacent after a win in Italy, to come back three days later.
"I want to see the consistency levels of the group. That's why for me this is a massive mark of where we really are."
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Rosenior praised West Ham boss Nuno Espirito Santo, who took charge at the London Stadium earlier this season.
"I'm not surprised Nuno has put his stamp on the team," he said. "All of his teams have always been really well organised without the ball, whether that's a 4-4-2 shape or a 5-4-1 without the ball.
"And they've always been very good in transition moments."