The former Ajax star played for 70 minutes in the Magpies' loss to Club Atlas in Milwaukee this week.
Arriving after captaining the Dutch giants to a fourth straight league title, De Jong struggled with injuries all season in the North-East, and was unable to play a part in what was at times a desperately disappointing season for the Magpies.
It has meant he is fully focused on what he wants from his second campaign at the club.
“It’s going to be a really important season for me and the key thing is to stay fit," he is quoted as telling the Chronicle. "I am doing all I can to stay fit and play as much as I can and train as hard as I can, so I can play a lot of games this season.
“Last season was a tough season for me personally and also for the team."
There is positive news for the player after he featured in Newcastle's 2-1 loss to Club Atlas on Tuesday.
“I am feeling good," he said after the match. "I need games. I played a couple in the end and also with the Under-21s, but I needed a pre-season and that’s what I am getting now. It was a good 70 minutes today. Hopefully in the next couple weeks I get 90 minutes in.”
What can Newcastle expect from a De Jong fit and on form?
The Dutchman only managed five matches for the Magpies last season, which came off the back of a final season at Ajax when he also missed some matches, though he did manage to score in those limited appearances.
But what is noticeable about De Jong's game is that, in his last five years in Amsterdam he was a vital influence in the side's success and also a huge contributor of goals.
The 26-year-old took over from Jan Vertonghen as captain in 2012, promptly leading Frank de Boer's side to two more Eredivisie titles.
Arguably, of all the players that have left Ajax over the last five years, from Luis Suarez to Christian Eriksen to Vertonghen and Toby Alderweireld, it is De Jong's absence that was the most felt by the club once they sold him. It was that first year without the Netherlands international that the European giants failed to win the league title for the first time in five years.
With someone with experience of working in that culture like McClaren, a fit De Jong could be a massive improvement to the Newcastle from last season.