Both Januzaj, 18, and Lingard, 20, have shone in United's pre-season fixtures with the pair scoring in David Moyes' side's 5-2 win over Kitchee SC on Monday.
Now Smalling, who has established himself in the setup at Old Trafford since moving from Fulham for £7million in 2010, has backed the duo to feature regularly in Moyes' first season at the helm.
"They have taken their chance,” he told the club's official website.
"It’s good that the manager has given these young players a chance and they have really taken their chances.
"I think all of them have made a claim for the start of the season and they are all in with a good shout."
Januzaj himself has targeted progression as the main aim.
"I have done some good stuff (during the tour) and I hope to keep going," the Belgian added.
"That is what I am going to do. I am going to work hard and try to keep doing what I am doing."
United have one more friendly on their tour before heading back to England, which will see them face AIK in Stockholm on August 6.
