THE AFL remains committed to keeping Etihad Stadium's roof open during day games whenever possible, despite criticism from Melbourne coach Paul Roos and his Brisbane Lions counterpart Justin Leppitsch.

Players on both sides were affected at times by the ball moving between shade and bright light during the Lions' 23-point win, particularly in the second quarter, and Roos was incredulous the roof was not shut.

"I don't understand why it's open, because it's an indoor stadium," he said. "It's bizarre.

"I must admit I commented before the game, I said to the coaches I just can't understand why the roof would be open at Etihad.

"I don’t know the reason, but it's incidental in relation to the game."

Asked if the players mentioned any issues with the light during the game, Roos said it clearly had an impact.

 "You can tell it impacted, which at the MCG or SCG or wherever you play is not an issue," he said.

"It obviously impacted the game but that's another thing.

"We've got an indoor venue and you spend however many millions of dollars on it and you leave it open.

"I know the broadcasters don't like it. I just don't understand."

Lions coach Leppitsch said it was "terrible" that the roof was open and said it also affected the umpires' ability to make decisions.

"I spoke to the umpires before the game – they hate it because it's very difficult to look through the light," he said.

"They probably won't admit to that, but they told me privately that they're not happy with making those calls, sometimes it's difficult.

"You can see the players - how many times (did they hold their hands to their eyes)?

"There's a lot of games played in the sun but obviously the ground's built on a funny shape that the sun goes right in your eyes too.

"I think to a man every one (of the club coaches) voted to shut the roof but still they keep it open.

"But anyway, that's not up to me, that's a bit of a sidebar really of what's going on."

Players and umpires aside, fans sitting behind the goals at the Coventry End of Etihad Stadium appeared to struggle looking into the sun, particularly after half-time.

AFL spokesman Patrick Keane confirmed it was the AFL's decision to open or close the roof, and he said it would only be closed for day games if rain was likely.

"Other than that we leave the roof open because it's an outdoor game and we believe it's a better experience with the roof open compared to it closed," Keane told AFL.com.au.

"Yes, we're aware that there's people that disagree with that at times.

"But our view is that the roof should be open wherever possible for day games unless there's rain."

Etihad Stadium spokesman Bill Lane said stadium management liaised with the AFL match manager before day games but confirmed the roof was always shut for twilight and night games.

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