St Kilda mature-age recruit Tim Highmore will make his AFL debut in Sunday's clash against the Giants.

The Saints confirmed in a statement on Friday morning that the defender will play his first game in the GIANTS Stadium clash.

Highmore, 22, was drafted to the club with Pick 45 in the 2020 National Draft and now gets his opportunity amid a host of injuries in the backline, with Jarryn Geary, Ben Paton and James Frawley all sidelined.

"It will be great for him to play and he's really looking forward to it," Saints coach Brett Ratten said on saints.com.au.

"He kicks the ball well, he's brave, he's a good sizeโ€ฆ so whether he's a second-tall defender or third he's sort of in that category.

"There's so many stories about how you got an opportunity to play the game... some have had to work (through) different paths and different challenges.

"Players have got their own stories, but they all have the opportunity to make a mark on their own AFL careers."

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Ratten in an earlier interview in February described Highmore as a "(Callum) Wilkie clone".

โ€œYoung Tommy Highmore is nearly a Wilkie clone in the way he goes about it, but heโ€™s a right-footer and he played exceptionally well mopping up,โ€ Ratten said.

โ€œHe kicks the ball well, heโ€™s brave, heโ€™s a good sizeโ€ฆ so whether heโ€™s a second-tall defender, or third, heโ€™s sort of in that category.

โ€œIs he going to play round one? Weโ€™re not sure. Is he going to play this year? Weโ€™re not sure.

โ€œI had a one-on-one meeting with him the other day and we spoke about that; itโ€™s about getting your opportunity and taking it and heโ€™s up for the challenge.

โ€œAt 22, heโ€™s a long-term view too, for us. Whatever he does this year will be a bonus because he will improve, he will adapt to the AFL (and) the way itโ€™s played.

โ€œHeโ€™s already mentioned: โ€˜Gee, itโ€™s a bit quicker, if you donโ€™t get your positioning right you get caught outโ€™. And Iโ€™m like: โ€˜Exactlyโ€™.โ€

St Kilda and GWS will meet at GIANTS Stadium on Sunday at 3.20pm AEDT.