Willock missed last weekend's home defeat to parent club Arsenal because of the terms of his loan agreement, but is expected to return to the Magpies' squad for the trip to the King Power Stadium.
And Bruce says the 21-year-old's recent displays, which have seen him step off the bench to bag three goals in his last four outings, have given him food for thought as he plots a way to get the better of the in-form Foxes.
"He came in against Southampton, I think his first game was, and did very well," said the United head coach.
"Every young player can go up and down a little bit, but certainly he’s been knocking on the door, of course he has.
"He’s had a terrific time for us, with four goals from midfield in eight, nine or ten games, so knocking on the door is the polite way to put it."
Aside from the injured skipper Jamaal Lascelles and the suspended Fabian Schär – who saw an appeal against his red card against the Gunners rejected this week – Bruce says he has a fully fit squad to choose from for the game against Brendan Rodgers' men.
And he also delivered some encouraging news on the fitness of forward Callum Wilson, who came through 90 minutes last time out in what was his first start since suffering a hamstring injury in February.
"Everybody is OK. As you know, we lost the appeal with Fab so unfortunately he’s not available, but everybody has come through unscathed from the weekend," he said.
"(Wilson)’s over his injury, which is vitally important. He’s had 90 minutes under his belt, so that’s only good for him and his mental state as well – that he knows that his hamstring is OK."
The Magpies are currently nine points clear of the relegation zone with four games remaining.
But with two tough games to come in the next seven days and safety not yet mathematically secured, Bruce wants his charges to focus on the task ahead of them, with their points advantage over the bottom three meaning their Premier League status remains “in our hands”.
"If we beat Leicester then we're virtually there," he said. "I think you can’t take anything for granted in the Premier League. We're a lot healthier than we were six weeks ago so for that, I'm absolutely delighted.
"It's been in our hands, and still is in our hands. We couldn't have wished, though, for any more difficult games than the two we've got coming up. Leicester, with what they've done and what they've achieved and to be in amongst the company they’re in, it's a very good side they've put together, and of course Man City next week.
"We've got some tough games coming up, and that’s the Premier League. But its still in our hands, which is good."
On Rodgers' Champions League-chasing Foxes, Bruce added: "They're quite remarkable and you have to just compliment them. When you think of the teams they're in and around, they just missed out on the Champions League last year, and look to me as if they're going to be in it this year.
"They've bought well, they've sold well, and they've improved their team. You have to tip your hat to them, especially Brendan. I call him young – he’s not so young anymore – but (he's) a British manager doing so well, because he has put together a very, very, very good team, which is going to be a difficult ask to try and get something
