The Geelong draftee, who only turns 19 next month, will play his first game at home against North Melbourne.

In a surprise selection by the Cats, the Albury Tigers' junior was named in the back pocket when the club announced its extended squad late on Thursday.

The 198cm O'Sullivan has played two matches for the Cats in the VFL and was named in their best players a fortnight ago against Box Hill.

His father Jamarl, a premiership player at Albury, was naturally delighted to hear the news.

"He's been working extremely hard for this and it will give him a taste of the grade and see if he's up to it, so hopefully it goes alright and gets it (the debut) out of the way," he said.

Jamarl plans to attend the game, but is battling illness after only just returning on Wednesday from climbing Mount Everest base camp, which is more than 5000m.

"I'm literally going into a sauna this afternoon (Friday), so I can try and get rid of the flu to get down there," he offered.

Connor O'Sullivan was back to watch the Tigers last weekend.

"It shows that hard work pays off," Albury co-coach Shaun Daly said.

"He's an extremely hard working and dedicated person, but also very humble and appreciative of the people around him.

"The first chance he had he came back to Albury and had a chat with our juniors and watched all games last weekend.

"We are super proud."

The athletic teenager joins local products Shaun Mannagh and Darcy Wilson as former O and M players to also make their AFL debuts this season.

Mannagh played the first two matches for the Cats before missing the past fortnight where he was named emergency.

He was also named on the extended bench on Thursday night.

O'Sullivan played for the Murray Bushrangers last season, as well as Albury, including the grand final for the league powerhouse.

He kicked a goal late in the grand final from a tight angle after taking a mark deep in the forward pocket.

The Cats enter round five as one of three undefeated outfits, joining GWS and Carlton.