* Australia win toss, choose to bowl (updates at tea)
By Nick Mulvenney
SYDNEY, Jan 3 (Reuters) - Mahela Jayawardene scored his first half century away from home for more than three years to help Sri Lanka reach tea at 169 for four on the opening day of the third and final test against Australia on Thursday.
The Sri Lanka captain, playing his final test in the role, fell victim to Mitchell Starc for 72 an hour before tea and was followed to the dressing room by Thilan Samaraweera (12) just before the break.
Lahiru Thirimanne (37 not out) continued to thwart Australia's four-strong pace attack, however, and will resume after tea with captain-elect Angelo Mathews, who had yet to score.
Australia skipper Michael Clarke won the toss and put the tourists in to bat on a sunny Sydney morning in a bid to take the early initiative in their quest to wrap up the series 3-0.
The least experienced of his pace bowlers, Jackson Bird, removed both Sri Lanka openers in the opening session but Jayawardene came out after lunch as if determined to make his opposite number rue his gamble.
The 35-year-old, forced to make four changes to his side because of injury, started to find his strokes on a good wicket and hit 13 boundaries in his 154-minute knock.
His 44th test fifty came up in fortuitous fashion, however, when he edged the ball off Mitchell Johnson just past second slip for a four.
Starc, who was rested for last week's innings and 201-run victory in Melbourne that secured the series, removed him with a fizzing ball that caught a thick edge and flew to Clarke in the slips.
There was a nervous wait for the raucous crowd at the Sydney Cricket Ground while a check was made for the no ball, but the TV pictures confirmed that Starc's heel had grazed the white line.
Peter Siddle, man of the match in the the first test in Hobart, had enjoyed a quiet day by his standards but then summoned up a peach of the ball to trap Samaraweera leg before in a decision that brooked no challenge.
Bird had made an early breakthrough in the eighth over when he had Dimuth Karunaratne caught off a top edge by Mike Hussey for five and returned an hour later to dismiss Tillakaratne Dilshan, caught behind for 34.
Thirimanne, who arrived in Australia only three days ago as a late reinforcement, almost became Bird's third victim when he was given out lbw on the next ball.
An appeal to the TV umpire confirmed the ball pitched outside leg and would then have missed the leg stump and the 23-year-old survived to bring up the 100 for his team with his first four.
Hussey, playing in his final test before retirement, got a huge cheer when he was handed the ball for two overs before the tea break but he was unable to snare what would have been a popular wicket. (Editing by Greg Stutchbury/Peter Rutherford)