Newcastle manager Eddie Howe remains "confident" Alexander Isak will still be at the club at the start of the season after the striker was left out of Saturday's 4-0 pre-season friendly defeat by Celtic.

The 25-year-old's future has been unclear after being the centre of transfer interest this summer.

"I think it's difficult for me to give 100% clarity on any player," said Howe after the disappointing loss at Celtic Park. "I'd never sit here and do that because it's football, and you never know what can happen.

"But Alex is happy at Newcastle. He loves the players he plays with, the staff, the team, and I've never had any issue with him.

"I'm confident he's going to be here at the start of the season."

Sweden international Isak, along with Brazilian midfielder Joelinton, was missed as the Scottish champions well beat Howe's side.

Celtic went ahead after 28 minutes when Arne Engels sent Nick Pope the wrong way from the penalty spot after being brought down by Joe Willock inside the box.

Keeper Pope made a major error to gift the hosts a second just before half-time, rushing off his line and failing with an attempt to head a long ball clear to allow Johnny Kenny to pass it into the empty net.

Newcastle brought on Anthony Elanga, who joined from Nottingham Forest earlier this month for £55m, for his debut at the break, but the winger could not make an impact.

Celtic added a third seven minutes after the restart when South Korean Yang Hyun-Jun slotted past replacement keeper Martin Dubravka from close range.

Despite Newcastle having more possession in the second half, they conceded a fourth goal as Liam Scales powered a 75th-minute header into the top corner.

The Magpies face Arsenal in their next pre-season game on Sunday, 27 July, in Singapore (12:30 BST).

On whether Isak will be part of the tour, boss Howe added: "Yeah, absolutely. He's part of our squad. At this moment in time, I expect him to come."