Australian leg-spinner Stuart MacGill, who is fighting for form and fitness, is considering retiring from Test cricket and will make a decision on his future before the Boxing Day Test against India.

The 36-year-old has not set a deadline, but confirmed he will not nominate for selection unless completely certain that his knee can withstand the rigours of Test cricket, according to a report in The Age.

"In my career, every game is a big game and every day is a big day. But those days are numbered and you never know when the end is going to be," MacGill said.

"It will depend if there is improvement. If I understand it correctly, there are new, degenerative issues. There is no guarantee the knee will ever get better.

MacGill, who has 203 wickets in 42-Tests, said, "No bowler is 100 per cent  only 20-year-olds are 100 per cent  and the great bowlers have always been able to play with pain. But there is a difference between playing with pain and not being able to contend with the demands of the game," he said.

"We have got India coming up and I will have to be on top of my game. My intentions? I alone will know what condition I am in and two days after a Test is not the best time to make a decision," he said.

MacGill was unable to replicate his form of past seasons, in the series against Sri Lanka [Images].

"I still want to be the best spin bowler in Australia in 12 months and I hope that will be the case. I guess I will just know if I am ready. I will never go into a game I think I can't finish."