Newcastle United have invested heavily in the close season but manager Eddie Howe said on Friday they still need one more addition to improve squad depth as they fight on two fronts in the Premier League and Champions League.

Newcastle spent 128 million pounds ($162.60 million) on bringing in Sandro Tonali, Harvey Barnes and Tino Livramento in the close season.

But with the club qualifying for the Champions League for the first time in two decades, Howe said he would like to reinforce the squad.

"I'd love one more player personally and I think then we'd have the ideal depth at this moment with the injuries that we currently have, let's wait and see," Howe told reporters ahead of their Premier League opener against Aston Villa on Saturday.

"Not 100 per cent (sure of signing more players) because it depends on the deal and I think we may have to be creative with this last player.

"But it's difficult to make that a definite because, again, it depends on injuries between now and the window shutting."

The manager confirmed Joe Willock, who missed the end of last season with a hamstring injury, remains sidelined at least until mid-September.

"He has just felt a little bit of discomfort in his hamstring, not necessarily another pull to the area," the 45-year-old manager said.

"We will probably miss him for the first group of games before the first international break."

Howe did receive a boost with defender Fabian Schar returning from injury, saying that he has been training well.

Newcastle moved early to bring in midfielder Tonali from AC Milan, with the player signed in early July, and Howe said he is happy with how the Italian player settled in during pre-season.

"I think when you're bringing players from abroad you have to try and get them early. I have to compliment Sandro on how he has handled the move and how he is adapting to the changes," Howe said.

"We're pleased to get the majority of our business done early and I think we're in a good place."