CHRIS Fagan says Brisbane's inclement weather might decide who replaces injured Cam Rayner for the Lions' season-opener against Sydney at the Gabba on Saturday night.

The Lions appear to have 21 of their 22 players locked in, but with Queensland's capital forecast to receive anywhere from 10 to 25mm on game day, the final spot is up for grabs.

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Rhys Mathieson and Ely Smith played a practice game against Gold Coast, while draftee Harry Sharp impressed when coming on to replace Rayner in the Lions' AAMI Community Series win over the Suns.

"The weather can play a factor in that tomorrow night, there's a little bit of rain around," the Lions coach said.

"We've just got to work out the type we want in the game."

Sharp is the bolter in the frame after being taken with pick No.43 in the NAB AFL Draft.

Fagan admitted the former junior national steeplechase champion had jumped up the pecking order in his first pre-season as he juggled Year 12 with starting his football career.

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"He got the opportunity when Cam went off in the Gold Coast game and he probably did better than we expected to be quite truthful," Fagan said.

"We gave him that opportunity thinking he might get 15 minutes and give him a taste of AFL football, which would be good for his development, but as it turns out he got two-and-a-half quarters and had quite an impact.

"He certainly came from a long way back before that game and has put himself in the frame.

"Because he's been an elite athlete he understands how to train and prepare at the elite level."