Mateta is enjoying a first full preseason in two years for Palace.
As Glasner explained ahead of today's Wembley clash: “JP had a difficult start to last season because of the Olympics tournament.
“He was away pre-season, then also emotionally, having the Olympic Games in your country, then losing the final… then it took him a few weeks to be ready again.
“From that moment, he came back and started to score again. In pre-season, he's our top scorer, he’s getting assists as well, he knows exactly how we want to play it, and he knows if he invests so much in what he's doing in every single game, he will get the chances and he will score the goals – so I’m very positive that he will continue scoring goals for us.”
Glasner added: “We love these games. I think I mentioned it before in the FA Cup: go into any school, ask girls and boys where you want to play when you play football – ‘I would like to play once in my life at Wembley.’
“We all experience it now for the third time within three months, so that means we are living out our childhood dreams. This is how I always will see these games.”