Though he has played well in recent weeks, Williams has failed to score since the Boxing Day win at Notts County – his longest goal drought of the season.
Marquis is confident Williams will soon add to his nine-goal tally for the season.
And he insists the 30-year-old’s makes a vital contribution whether he is scoring or not.
“Willo has made a great career from scoring goals and you don’t lose that overnight,” Marquis told The Star.
“For me, as a pair, we work hard together.
“You see some pairs where one does all the running and the hard work and the other takes the glory.
“I don’t think it’s like that here.
“We both put in a good shift, both score goals.
“Willo has come back from injury and it might take a while for him to really get his sharpness back.
“But we know he’s going to score goals between now and the end of the season.
“There’s no doubt about that.
“He’s going to be a massive part of us moving forward.
“I’m sure he’ll be focused on his performances and I feel they’ve been very good of late.
“I think they help me. His running to create space for me and other players.”