The on-loan winger set up both goals in his side's 2-0 win away to Heidenheim in the Europa Conference League on Thursday.
Sancho started the match and played the full 90 minutes as he stepped up his return to action.
The 24-year-old had not been named in a starting line-up since the loss to Liverpool on October 20.
Meanwhile, his five-minute cameo against Leicester on Saturday was his first appearance for six matches.
Maresca has now explained what Sancho must do to become a regular starter for the Blues.
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The Italian remarked: "I said since we started, Jadon is very important for us.
"He has to be fit, mentally and physically and he is going to help us a lot.
"Unfortunately we did not use him in the last few games.
"But he is showing tonight how important he is.
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"We need that quality in the last third against a low block. He is going to help us a lot."
Sancho provided assists for both Christopher Nkunku and Mykhaylo Mudryk as Chelsea maintained their perfect start in Europe's third-tier competition.
The Blues have won each of their first four matches to assure at least a play-off place with two fixtures remaining.
As for Sancho, he now has five assists in just seven appearances for Chelsea since signing on loan from Manchester United on deadline day.
He will hope to keep his place in the side for the visit of Aston Villa on Sunday afternoon.
And his display against Heidenheim caught the eye of ex-Tottenham centre-forward Peter Crouch, who believes he is showing his quality with every game he plays.
The former England striker told TNT Sports: "He was involved in a lot. He's got such quick feet, creativity.
"When he's confident, he's as good as anyone and seems to always pick the right pass.
"He's getting up to speed, but when he's fit and playing well, this is what he can do."
As for Chelsea icon Joe Cole, he added: "Sancho was fantastic again."
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