* Smith scores 17th century
* Australia hold 22-run first innings lead
* Rain brings tea early (Updates at tea)
By Ian Ransom
MELBOURNE, Dec 29 (Reuters) - Captain Steve Smith raised a composed century to push Australia to a 22-run first innings lead before a storm brought tea early on day four of the second test against Pakistan on Thursday.
Smith was unbeaten on 100, with Mitchell Starc on seven not out, as Australia moved to 465 for six in reply to the tourists' 443-9 declared at the Melbourne Cricket Ground.
Rain could ultimately dash Australia's hopes of forcing a result and wrapping up the three-match series 2-0 with a game to spare, but Smith's side may yet set Pakistan's batsmen a task on day five.
Australia resumed after lunch on 395 for four and Smith pulled a short ball from Sohail Khan for four on the first ball of the session to notch his 1,000th run for the year.
Number six batsman Nic Maddinson fell for 22, bowled when skipping down the pitch to take on legspinner Yasir Shah.
Rookie Maddinson was already under pressure after a string of failures in his first two tests and the unconvincing 55-ball innings may not be enough to keep him in the side for the third and final match in Sydney.
With the game slipping away from Pakistan at 447-5, wicketkeeper Matthew Wade slogged Yasir into Azhar Ali's helmet as he fielded at short leg and the opening batsman slumped to the ground in pain.
After a few minutes to recover, he walked off the ground groggily with medical staff.
Wade was also under pressure, bringing scores of four, seven and one not out since his recall in the dead rubber test against South Africa in Adelaide.
He did himself no favours, slashing at a wider Sohail delivery to be caught by Asad Shafiq in the slips for nine.
Smith remained resolute, however, and as ominous rain clouds moved over the stadium, he cut Sohail for three runs past point to bring up his 17th century from 168 balls.
Usman Khawaja earlier missed out on a sixth ton, adding only two runs to his overnight total of 95 before he was caught behind playing a loose drive off paceman Wahab Riaz.
Khawaja's wicket was a reward for some rare sustained pressure by Pakistan's pacemen but they promptly loosened their grip, allowing Smith and Peter Handscomb to race to a 92-run partnership on a hot and humid morning.
Handscomb marched to his half-century, his third score over 50 in his first three tests, but was out for 54 when he sliced Sohail straight to Sami Aslam at point.
(Editing by Greg Stutchbury)