COLLINGWOOD forward Will Hoskin-Elliott's delayed start to the season was due to a large, unsightly "ball of fluid" on his left knee that had to be drained several times.

The pacy high-flyer had undergone minor surgery on the iliotibial (ITB) band – a large tendon running along the outside of the leg, crossing both the hip and knee joints – and had hoped to be back within five weeks to play in the season-opener against Geelong.

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However, an excessive build-up of fluid on the outside of the knee led to the development of a soft lump that was slow to respond to treatment.

Literally and figuratively, Hoskin-Elliott's return date became a fluid situation. He ended up missing the opening five rounds.

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"It was frustrating because we'd set timelines and a few times we were set back a bit by this big, weird-looking thing on the side of my knee," Hoskin-Elliott told AFL.com.au.

"It just blew up. It was in between the size a golf ball and a tennis ball.

"We drained it three or four times but the big ball of fluid just kept coming back. That was annoying because it kept me out, but eventually it settled down.

"The ball is still there even now. It's a fair bit smaller, but when I bend my knee it still pops out. It doesn't give me any problems though."

The trigger for Hoskin-Elliott's knee problem can be traced back to an incident 11 months ago when he was lucky to avoid a serious injury to his other knee.

In the win over Essendon in round 16 last year, Hoskin-Elliott copped forceful front-on contact to the outside of his right knee, leaving him writhing in pain. After hobbling from the field and being assessed by the Magpie medicos, the knee was heavily strapped and he later returned to the fray. He was relieved when scans revealed he'd escaped with just bone bruising.

The versatile Pie didn't even miss a game on his way to kicking a career-best 42 goals – second at Collingwood behind only Jordan De Goey's 48 – in a team that came within a whisker of a premiership.

That mishap against the Bombers was to have a residual effect.

"It actually changed my mechanics and made me walk differently," the 25-year-old said.

Consequently, his good left knee over-compensated for his bad right knee, and eventually his good knee became his bad knee.

When pre-season training resumed in December, Hoskin-Elliott soon felt discomfort in his left knee. Something wasn't right.

He consulted a surgeon and was told that the injury should repair itself with rest.

It didn't heal at all. In fact, over the next two months it worsened and became sorer. Even so, it came and went.

"It was a weird one because I could do a full training session but the next week I could only do half a session, but the week after that I'd do a full session again. It got to the point where it was like, 'No, you're not doing anything,'" he said.

The only option was surgery, and Hoskin-Elliott went under the knife on February 18.

He was out of action for the first time as a Magpie. After the former Giant was granted his wish for a trade to Collingwood – the club he'd supported as a youngster and which his great-great-grandfather Charlie Norris had won a premiership with in 1910 – he was just one of three Magpies to play every game in 2017-18. (The others were Steele Sidebottom and Jack Crisp.)

But rehab wasn't new to Hoskin-Elliott, who as a Giant spent considerable time recovering from various injuries.

The fluid complications had the Pies at one stage forecasting that he wouldn't return until round seven or eight, but he made it back in round six for the Anzac Day clash with Essendon.

After such a long layoff, Hoskin-Elliott had been preparing to play in the VFL and was "shocked and rapt" to be given an immediate AFL senior call-up after small forward Jamie Elliott was ruled out with a corked buttock.

"To come straight back in gives you a huge amount of confidence because you know you've got the backing of the coaches," he said.

Hoskin-Elliott has played the past six games, averaging 14 touches and a goal a game, being held goalless just once.

His first four games were "a bit of a struggle" form a fitness perspective but in his past two outings he has returned to the level required to fulfil his preferred role as a high half-forward with the occasional burst on a wing. He's building momentum ahead of the Queen's Birthday clash with Melbourne at the MCG on Monday.

The quietly-spoken Hoskin-Elliott takes it all in his stride. Still living in Melbourne’s west after growing up in West Sunshine and first playing for North Sunshine, he and wife Kirstie have a one-year-old son Flynn. Fatherhood has enriched his life, including his football.

"The little fella takes my mind off everything. He gives me a mental break. Being a Dad is awesome. He's at that stage where he's pretty much doing something new every day. I could watch him all day. He's already got a few footies and he absolutely loves them," he said.