Australia's merry-go-round of spin bowlers may be about to slow down. SCOREBOARDAUSTRALIA'S merry-go-round of spin bowlers may be about to slow down, and perhaps even grind to a halt.Before yesterday, Nathan Lyon would hardly be recognised in his adopted home town of Adelaide. He had played only five first-class matches and taken 14 wickets. He is guaranteed a few more second glances now.There is also little chance of seeing him behind the wheel of a lawnmower at Adelaide Oval any time soon.On an extraordinary second day of the first Test against Sri Lanka in which batsmen dropped like dominoes - there were 16 casualties in all - the 23-year-old off-spinner led the tourists into a commanding position, taking five wickets, including one with his first ball in Test cricket.Before tea, the host had been rolled for a paltry 105 in response to Australia's suddenly imposing 273. Australia then had its own issues coping with a devilish pitch but will start today at 6-115 - a lead of 283 - after captain Michael Clarke guided his team further ahead.If yesterday was any indication, Australia might well be celebrating at its plush ocean-side hotel by mid-afternoon.While Clarke batted sublimely for 60 in the fading light and tough conditions, producing his best display with the bat in recent memory, there could be no overshadowing Lyon. The 11th spinner used by Australia since the retirement of Shane Warne in 2007, he shone on a Galle International Stadium track that has been a batsman's worst nightmare.He was not without company in tearing Sri Lanka to shreds. A reverse-swinging Shane Watson (3-11) ripped through the heart of the Sri Lankan order with a trio of key scalps in the space of only two overs, and another first-gamer, Trent Copeland (1-24), was also excellent.The NSW medium-pacer captured the first wicket of a frenetic day with just the second delivery of his Test career - the victim was captain Tillakaratne Dilshan - thanks to a brilliant catch by Ricky Ponting. Later, Copeland's lovely back-handed flick from point ran out Mahela Jayawardene.Lyon's return of 5-34 was the best debut from an Australian bowler since the 8-215 claimed by Jason Krejza in Nagpur in 2008.''It's been one of the best days of my life,'' Lyon said. ''To be able to take five wickets on debut is pretty special.''Lyon had a dream start, dismissing Kumar Sangakkara for 10 with his first Test delivery. It was a ripper of a ball, spinning ferociously and prompting a prodding Sangakkara to find an edge. Clarke snapped it up with a fine, low one-handed grab, and Lyon was bombarded by teammates.''I couldn't breath in the huddle,'' Lyon said. ''I was so excited. I wouldn't say it was the perfect ball ? but I was pretty happy with it in the end.''Lyon became only the 14th cricketer in Test history to claim a wicket with the first ball of his career, and the only Australian since Arthur Coningham in 1894-95.